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FAQs on Tapwater Filtration: Reverse Osmosis, Deionized, Distilled Water System Selection

Related FAQs: RO/DI & Distilled Water 1, RO/DI & Distilled Water 2, RO/DI & Distilled Water 3, RO/DI & Distilled Water 4, RO/DI & Distilled Water 5, RO/DI & Distilled Water 6, RO/DI & Distilled Water 7, Rationale, For Commercial/Large Output, RO Water Storage, RO Water Treatment,  Maintenance/Repair, Deionizing Source Water Filtration, Kati-Ani DI Units, Kold-Steril Units, Water Make-up, Nitrates, 

Related Articles: Water Purification Using Reverse Osmosis, Reverse Osmosis, A Multipurpose Tool By Mark E. Evans, Water Changes, Water Quality, Synthetic or Natural Seawater, Nitrates, 

We use a "cheapy" warehouse store unit... and change the carbon pre-filters often (every couple of thousand gallons)... the RO membranes about every ten pre-filter changes... Bob Fenner

Source water for SW sys., switching an African Cichlid set up to marine  – 10/10/08
Hi all,
<Marc>
I have a 75 gallon tank, with 80 lbs of live rock, a Remora Pro protein skimmer, an Emperor 400 that I just run filter pads with no charcoal, two Hydor stage 4 power filters, and a stage 3. For livestock I have a Yellow Tank, three Green Chromis, Lawnmower Blenny, Firefish, Chalk Bass, Six Line Wrasse, Cleaner Shrimp and assorted snails and crabs.
My question is about water changes. I do about a 15% water change every Friday. I test my water, add the necessary supplements, usually calcium and a dKH buffer. I use tap water and mix in Reef Crystals about 15 minutes before i add the water. I know it's not ideal,
<Mmm, we'd have to discuss, agree on what is "ideal"... IF your system is doing what you want it to do... the livestock fine... this would be ideal to/for me>
but it's not practical for me to treat the water earlier because of a small living space, and my girlfriend not being as enthusiastic as i am, doesn't want two buckets of water kicking around the apartment. And since i only have one day off, I like to get tank done first thing in the morning, and the pet store isn't open early enough for me to buy r/o water.
<I use RO for drinking, cooking... tap/mains water for my own tanks>
Now that I'm done making excuses, here's my question. Would I be better of doing a water change every other week? It doesn't seem like my mushrooms open up all the way until a couple days after the water change every week. I was wondering, if would be less stressful for the tank, to only do the water change every other week.
<Worth trying out>
Thanks, Marc
P.S. I also have a 75 gallon African Cichlid tank. I was thinking about switching it over to a saltwater tank. My question is, I have about 100 lbs. of lace rock in there, and about 80 lbs. of live freshwater cichlid sand. Could I use the rock and sand for a saltwater tank?
<Mmm, some "lace rock" has a good deal of phosphate (can be tested for in a few ways)... and would need to know what the make-up (even just Brand, name of product) of this sand... but it can likely be added, blended with something a bit more soluble, otherwise useful. Bob Fenner>

Reverse Osmosis Filters…Cheaper Than Realized? – 08/07/08
Unfortunately, I did not research prior to buying a used Kent Marine 24 gallon per day unit for the price of $125.
<<Mmm, yes…a bit of looking around could have found you a “new” 75gpd RO/DI unit for about $10 more>>
I need to replace the membrane, and all three filters of this unit.
<<Easy enough to do…these units are all pretty much “standard” and the membranes/other components are easily interchangeable>>
I can upgrade the unit to produce 50 gallons per day, but the cost will be $183 to do this. Add this to the $125 cost of the filter, and I cannot help but wonder if I should just purchase a new SpectraPure reverse osmosis filter that will produce 100 gallons per day, at $199 plus shipping.
<<SpectraPure is a good product (is what I have), but you can use your current housings and upgrade your membrane and flow restrictor here (http://www.thefilterguys.biz/ro_membranes.htm) for a mere $56…plus a little more to replace the other components>>
Unfortunately, I already spent $125 for the unit, so an additional $183 to replace the filters and upgrade the capacity to (still) only 50 gallons per day will mean I am spending almost $300 for the unit!
<<Do look in to the link I have provided>>
I guess my question is: is the Kent Marine filter such a superior product that it warrants such a price ($260 new) for a filter that only produces 24 gallon per day?
<<This is for an RO/DI unit? Hardly… Most of these units and components are made by a few manufacturers (e.g. – DOW) and then distributed and remarketed/relabeled for selling by the different vendors. Have a look around on line at the independent vendors (even those not from the hobby interest)…this technology is not/should not be that expensive to utilize>>
Regards,
Jeff Castaldo
<<And to you. Eric Russell>>

Re: Reverse Osmosis Filters…Cheaper Than Realized? - 08/08/08
Thanks so much for your quick reply.
<<Quite welcome>>
I went there, and these guys are even cheaper than waterfiltersonline.com!
<<Indeed… TheFilterGuys.biz is a great place to get your RO/DI systems and replacement components. I go to them for my own needs…service is excellent>>
I am new to your website, but I can see it right now that I am going to enjoy it immensely.
<<Ah, welcome then>>
Regards,
Jeff
<<Cheers, EricR>>

Reverse Osmosis…Is This A Good System? – 04/07/08
Good evening Sir,
<Many Ladies here as well…but EricR here with you this afternoon>>
I've had an FO tank for over 4 years now, doing fairly well. Would to move to FOWLR and finally reef eventually.
<<Seems to be a popular progression for many>>
Problem is that I live in India, and have absolutely no help on proper practices and access to equipment.
<<Mmm, well…the Internet can likely help with both>>
I understand that RO is vital for a healthy reef and since I can't purchase that around here, was wondering if something like this could be used instead? http://www.kent.co.in/excel.htm
<<It could be, yes…>>
Would really appreciate any help that you could offer.
<<I’m not sure about shipping internationally, but I think it would be worth your time to have a look here (http://www.thefilterguys.biz/index.htm). Send them an email and explain your situation…if they can/will ship to you, I’m sure they will design a system to fit your needs at a fair price. Oh…and do spend some time reading/researching the abundance of data on our site re FOWLR and REEF systems. Use the Google search box at the bottom of the homepage to perform keyword searches for topics of interest>>
Loved CMA.
<<Me too!>>
Thank you, Adriel Rebello
<<Happy to share. Eric Russell>>

Tap Water Parameters…Is a Filter Necessary - 03/26/08
Sorry to bother you all again, Crew.
<<No worries>>
I have been reading that I may not need an RO/DI unit and may be able to use my tap water by letting sit and buffering for a day or two.
<<Depends much on how it will be used/what type of system you have (e.g. – reef/FOWLR/FO). Some folks can/do get away with not pre-filtering their water. But there is so much that could be in your water that you don’t/won’t know about (fertilizers, pesticides, etc.) that for me, the investment in an RO/DI filter for marine systems for sure, is money well spent. Even the “known” issues probably fluctuate in their levels so obtaining an analysis doesn’t likely give a true picture of water quality. Heck, when I lived in England for a time I discovered the town where I lived would periodically flush something through the system to kill the freshwater shrimp living within. Since I was not pre-filtering my water back then you can imagine the effect it had on my reef tank (twice!), before I discovered what was happening and began filtering my water as a result>>
Here is a list of my local water parameters. Do you think I am a good candidate for an RO/DI unit, or can I just use my tap water?
pH = 7.5
Alkalinity = 35 ppm
Hardness = 100 ppm
Conductivity = 270 umhos
Chlorides = 50 ppm
Chlorine = 2.5 ppm
Ammonia = 0.08 ppm
Iron = 0.01 ppm
Manganese = 0.02 ppm
Phosphate = 0.84 ppm
Sodium = 30 ppm
Copper = 0.09 ppm
Fluoride = 0.25 ppm
Lead = 5.8 ppb
Nitrate = 0.48 ppm
Nitrite = 1.0 ppm
<<The presence/levels of Ammonia/Nitrite/Nitrate cause me concern…I think the RO/DI unit will be a worthwhile investment regardless of the type system>>
Thanks again for your help
Matthew Diethorn
<<Quite welcome. EricR>>

RO/DI Systems 3/25/08
Good morning crew!!!
<Hello Mathew>
I am a bit confused about which water to use. I have a 55 gallon tank and currently buy RO water from my LFS. I do not want to do this anymore because it is a hassle, so I am looking to purchase an RO, DI, or RO/DI water system for my home. I am a bit confused about all of the differences in them. I do not really want any waste water. I believe I have read that DI units do not produce any waste water but the chemicals can be hard to deal with when recharging or replacing. Does an RO/DI unit produce waste?
<Yes.>
What do you recommend as the best option for me?
<A DI filter alone is not going to give you pure water. Depending on the resins used, they will only remove selected contaminants. Is best to go with an RO or RO/DI system.
If waste water is a major concern, Spectra Pure produces an ultra high efficiency model with a waste ratio of 1/1 which is pretty good considering most units will have a 80% or more waste ratio. Look here for specifications on this unit.
http://www.marinedepot.com/ps_AquariumPage~PageAlias~reverse-osmosis-deionization_spectrapure_rodi.html
Also read here and related FAQ's/articles. http://www.wetwebmedia.com/h2opurifiers.htm Thanks for your help
<You're welcome. James (Salty Dog)>
Matthew Diethorn

Re: RO/DI Systems 3/26/08
Thanks for getting back to me so fast.
<You're welcome.>
I will deal with the waste. I only have a 55 gallon, so I do not need too much for water changes anyway. My last question is....are all of these systems pretty much the same or are some a lot better than others?
<I think some are better than others as far as efficiency and quality of the membrane.>
 Money is a slight issue. I don't want to spend too much. I found this on Ebay and it looks pretty good. What do you think?
http://www.abundantflowwater.com/html/aquarium_filters.html
<Not bad for the price. I'd go for it. A Coralife 3 stage unit generally sells for $120.00 at most etailers, but no DI filtering.>
Thanks for your help again.
<You're welcome. James (Salty Dog)>
Matthew Diethorn

Quest For The Infallible Purifier -03/17/08
Hello, I've been struggling with Diatoms for months now. My tank is 2 & 1/2 years old. I know that Diatoms feed on silicates so I couldn't figure out why I have clouds of them when the only water I've ever put in the tank is Deionized.
<Clouds of diatoms? Really?>
So I decided to increase the size and frequency of my water changes thinking that organics and maybe nutrients had built up over the years. This only seemed to compound the problem. So I tested the Deionized water for silicates and sure enough the Seachem test revealed a level of 4 mg/l. My Tap water Purifier's life isn't even half over. So do you know of a Deionizer that will perform better than the one I've been using? Maybe one that will thoroughly remove silicates up to 75% of the Ion-exchange resin's life? I don't understand why these resins stop removing silicates so soon. Do you?
<I'm not sure what brand/type of unit you're currently using, but most the RO/DI units sold in the aquarium business remove just about everything (all silicates, etc.). Spectrapure is one such good brand (in my opinion).>
Thank you, love the site,
Greg
<De nada,
Sara M.>

Re: Quest For The Infallible Purifier 03/18/08
Yes, clouds, but Your being surprised has got me thinking that maybe they aren't diatoms. Is it possible to have the clouds and not have them on the rock and panels?
<I honestly don't know what's "possible." But I've never heard diatoms described this way.>
Do they first cover everything else before they cloud the water?
<They don't usually cloud the water as much as they cover surfaces (rocks, glass, etc.). You might have a phytoplankton bloom in your water column. In which case, ironically, I would suggest the use of a diatom filter (or diatom powder used in an suitable canister filter).>
They certainly look like the diatom "dust" that I've read about in terms of color and particle size.
<Diatom powder is substantially different from the live diatoms than grow in our aquariums.>
I guess the best thing to do is send a sample to a lab. Do you recommend this? What would you do?
<If you want to, go ahead. It's always helpful to learn. Though, it might be more fun and educational to get yourself a good microscope (always a good investment for a reef aquarist) and try to see it for yourself. :-)>
Thanks
<Best,
Sara M.>

R/O vs. Distilled 03/04/2008
Hi,
<<Hello, Andrew today>>
Recently I sent an employee to a different aquarium to get water for our reef tank. The owner was very negative about R/O water (i.e., a poor attempt to duplicate natural water, etc). He said that distilled water was far superior.
<<I personally don't actually think there is any noticeable difference between the two types of water besides cost. Distilled water usually costs more to self produce than RO or RO/DI. Using in the marine aquarium, well, you wont really notice any difference at all. I certainly would not state that distilled is "Superior" to RO or RO/DI>>
Previously, in a pinch, we have used our tap water which is hooked to a distiller. However, I have never read anything about distilled water being superior. What are your thoughts?
<<As above. Mainly its down to cost. Most people realise this over time and go and purchase their own RO unit>>
Thank you, Kathye
<<Thanks for the questions. A Nixon>>

Water Treatment 2/22/08
Hello Crew;
<Hi John>
I am perhaps at a point where I can no longer deny that I will have to get some type of water purifier to generate sufficiently pure salt water for my 180 reef tank. For the past year I have been using store bought RO, in the hopes that once my Chaetomorpha is sufficiently established in my refugium, I'll be able to just use de-chlorinated, Lake Ontario, tap water (which actually tests below the detection limits for NO3, PO4, & SIO2).
Trouble is, while my Chaeto is growing okay, it is not yet sufficient to reduce the nuisance algae in the display. Meanwhile, the use of store bought water is getting pricey.
<Amen.>
In looking at the options, I find the profligate waste of RO and RO/DI to be unconscionable (I live in an area where I have to pay for my water use, and also, in a northern climate, using the waste water to water the lawn would only work half the year!).
<Could use for an ice palace:)>
So, I am leaning towards a DI system. The trouble with these seems to be that, without an RO as a "pre-filter", the resins don't last. Then I thought that a household water-softener would have all kinds of capacity, but it produces sodium-rich water while leaving the phosphate, nitrate, and silicate alone, and in fact removes the calcium and magnesium which we probably might want to keep anyway. In short, it removes the wrong type of ions.
Now I'm thinking; "Hey, why not just use an anion column to remove the negatively charged ions, leaving the positively charged ions, such as calcium, in the water?". I'm wondering if the reason DI resins are short lived is because they quickly become saturated with Ca+? So, if we don't bother trying to remove the calcium, the resin may last a whole lot longer.
<There are a few types of anion resins and selecting the right one for what you want to do is important. The basic general purpose anion is basically a de-alkalizing resin, wouldn't want to use that. The anion tannin resin is for removal of color, organics and tannins. The nitrate removal anion resin is a relatively new technology and is one of the first resins that favor nitrate removal over sulphates and other ions in the water. Then we have the anion silica resin which removes what it says. The ProSelect Company does manufacture all of the above resins, and if you would like more info on their products, you can contact them at info@swtwater.com.>
To this end, I thought a "cheapy" system could be built just using an AP "Tap Water Filter" (or similar product) with a household carbon block prefilter.
<If you think buying RO water is expensive, wait until you see the bill the AP filter runs up, very inefficient vs. cost.>
Once the original resin is "pooched", it could just be replaced with anion exchange resin rather than mixed resin.
The only trouble I see is if there are some cations that should still be removed; and adapting a column meant for a cartridge, for use with, say, Kent anion resin.
Do you know if this has been tried before? Does it seem viable?
<Do not, but let me give you a suggestion...is a method I use. I aerate my freshwater for 24 hours to remove any excess CO2, I then run this water through a canister filter with one unit of Chemi-Pure for another 24 hours. The end result is crystal clear freshwater with most if not all contaminants removed. Depending on the volume of water being changed, you may want to add more time to the Chemi-Pure process. Been doing this for years with excellent results, and is very cost efficient. After this process is done, do store the Chemi-Pure back into it's container for future use. I will do about 40 ten gallon changes before I discard the Chemi-Pure. James (Salty Dog)>
Regards;
John T.

RO/DI Filtration Units…Size Standardization/TFC Membranes – 01/10/08
Hello everyone,
<<Greetings Ryan>>
I have burned another workday reading WWM,
<<Ha!...don’t get caught!>>
there is a lot of great information out there.
<<Indeed>>
I have been looking at RO/DI units from The Filter Guys and had a couple of general questions.
<<Okay… And by the way…can speak from experience/will endorse The Filter Guys as a good resource for RO units and supplies>>
No matter which brand you buy the replacement filters are basically standard sizes right, you can buy replacements from other manufactures can’t you?
<<Correct. There are larger “commercial” units/components available, but usually unless stated otherwise, most all prefilters, carbon blocks, membranes, et al for “residential use” are sized/standardized to fit these units. You can even buy and use components from your local hardware or home store>>
I want to be sure I don't buy a unit that a couple of years from now I won’t be able to find replacement media or membranes.
<<Shouldn’t be an issue>>
Also they (Filter Guys) have 2 different 6 stage filters- both have 3 prefilters, but one has 2 RO and 1 DI and the other has 1 RO and 2 DI's. Is there a benefit to going one way or the other?
<<The unit with two “membranes” is designed for double the output. The unit with two “DI cartridges” just means you will be able to go longer between maintenance/media changes…no real value re “better” filtering capacity>>
Will 2 DOW Filmtec 75GPD RO's cause less waste water or more, or is this just to increase the GPD's and there will be the same amount of waste water.
<<Any increase in “gallons per day” results in a corresponding increase in “waste water.” There are ways to increase output versus the amount of waste water (e.g.- ensuring optimum water pressure and temperature), but for most locals, the concern for waste water from these units is overrated…in my opinion. If the thought of this really bothers you…divert the waste water to your garden (as I do), or even to your washing machine for use there>>
Is one RO and DI enough or is there benefit from having 2 of either.
<<The only benefit is if you need the additional output a double-membrane unit can provide. The double-DI unit; if functioning correctly, should remove everything it will on the pass through the “first” DI cartridge>>
Also are DOW Filmtec RO's the TMC's I read about on your site, I take it they are?
<<I think you mean “TFC” or Thin-Film-Composite…and yes, I do believe the “Filmtec” membranes to all be “composite” membranes. You “can” also use the CTA (Cellulose Triacetate) membranes, but these are not resistive to bacteria, and some consider them inferior to the TFC membranes and to have a shorter useful lifespan>>
Also I have read this on your site but want to confirm that I am better off installing the unit after the water softener right, my pre-softener water hardness level is 12?
<<Mmm, yes…the RO/DI unit should be the last stage of your aquarium-use water treatment>>
I realize this is a very convoluted question, but I am hoping to only make this investment once. If there is a different path I should be taking please point me in that direction?
<<Many choices out there… You can get as elaborate as you want/can afford, but in my opinion a four-stage RO/DI unit will serve most any aquarist’s needs (1st stage* 5-micron polyester filter, 2nd stage* 1-micron carbon block filter, 3rd stage* TFC RO membrane, 4th stage* mixed-bed DI resin cartridge). An “add-on” option you should also consider is a “membrane flush kit”…can greatly extend the life of your membrane>>
Thanks for all your help.
Ryan from Colorado
<<Glad to help. EricR from warm (72-degrees!) but rainy South Carolina>>

Tap water purification -12/25/2007
Ordered an RO system the other day from CostCo. only $140 with faucet, storage tank and I believe output is 50 GPD. better to have control of water. thanks for the response. I was concerned with the water bill (utilities are insane). anyhow, our bill is about $2.50 for every 750 gallons. Therefore, cost is not a concern and I will drain the water to lawn via our basement sump or run to garden.
<Ah, good idea!>
Would cost less than running a filter on tap 24/7 with average results and save cost on Brita filters.
<yep>
Only writing back so others can see, thanks again, love the site. mike in CT
<Thank you,
Sara M.>

Zero waste RO  11/16/07
Hi,
<Jae>
was wondering what you guys think/know about the Watts Premier Zero Waste RO system (Costco). was thinking of getting one. Seems like a very cost effective idea?
<Oh yes... A winner. CostCo makes few mis-purchases... (and backs all): http://www.costco.ca/Browse/Product.aspx?Prodid=10289835>
thanks as always
Jae Lance
<Welcome, Bob Fenner>

From Tap to RO Water  11/5/07
Hello
Our marine tank is currently set up using treated tap water (the advice we were given!) and we now wish to change to RO water.
<good>
We were thinking of purchasing RO water and using it for our future water changes but I am concerned about whether this may have any negative effects or cause any problems.
<Hmm, I'm not sure what you might be worried about. You're going from lower-quality water to higher quality-water. What could be the negative effects? Just make sure that when you add the new water (with each water change) that it's of the same/similar salinity, temp, alkalinity, pH, etc. as your tank water. But you should do that with any water you use for water changes (RO or tap).>
Our system is just a couple of months old and we have 2 common clowns.
Kind Regards,
Sian
<Best,
Sara M.>

Culligan RO water for Reef Tank 11/3/07
WWM- Hello.
<Hello, Scott V. with you.>
I have a 75 gallon tank with several fish around 90lbs of live rock and few corals. A friend of mine is an independent "water guy" - he sets up in-home water systems and such. He has been giving me five gallons of RO water ever 1-2 weeks to top-off my tank. But, it is getting to be a hassle to run to his house, or having him drop the water off at my house.
At our local Wal-Mart, Culligan has a station that sells water for 33 cents a gallon. I would much rather prefer to just pick up five gallons quick while shopping than have to depend on someone else to get my water.
It states that this water goes through a 4-stage filtration process. The source water is tap water from local municipal water systems. The four stages of filtration are: sediment filters, activated carbon filters, reverse osmosis, and UV light. Is this water to be trusted...have you heard of others using Culligan Water from Wal-Mart stores for reef tanks?
Thanks for all you do, WWM Crew!
<I have done this and tested water from various stations in my area to confirm what they claim (they weren’t necessarily Culligan). Fact of the matter is that some of the water was ok and some wasn’t. You could test the water for nitrates, carbonate hardness and even chlorine to confirm the filtration claims. Most local fish stores sell ro/di water that would be suitable. It would be easier and cheaper in the long run to consider your own personal reverse osmosis filter. Thank you for the kind words from the crew and I, Scott V.>

Re: New to saltwater- need for RO/DI filter? – 09/13/07
Hi. I've wrote to you a few times in the past about my 75 gallon FW tank. Well, the other day I caught my daughter "cleaning" the tank with half a bottle of Windex. After a complete tear down I've come to the conclusion that I would like to re-set it up as saltwater.
<Yikes. If you're going to start over again, venturing into saltwater, please do have a long discussion with your daughter (and other non-aquarist kids/significant other/everyone) about not touching your aquariums without asking you first.>
I've purchased Mr. Fenner's book and I must say, its a wealth of knowledge. I have a few questions I'd like to ask.
I've been looking into filtration. Fluval 305-405 canister filters are where my attention is turning. I've been researching filters from many places, looking at pictures, random message boards, and they all have pictures of sumps posted. Is a sump the best thing to use or would the Fluval canister be sufficient?
<A sump is usually preferred. The Fluval might be ok for a lightly-stocked fish-only tank, but it's going to be a real burden to clean. And you would have to clean it often. See here for more info on canister filters for marine systems: http://www.wetwebmedia.com/marcanistfltfaqs.htm>
I'll be using live rock to help with the bio-load and am interested in some anemone but these are not necessary now. My question is would my regular light be fine for the live rock? I know that I would need special lightning for the anemone.
<You don't necessarily need any special lighting for live rock.>
I've also been researching RO/DI units. Its within my means to get one but if I don't actually need one at first I'd like to save a little money.
<Get the RO/DI unit if you can. You'll absolutely need it if you ever want to keep an anemone. See here for more info on RO/DI filtration: http://www.wetwebmedia.com/rofaqs.htm>
(I have to hide all my receipts from my wife so she doesn't know how much I've spent so far).
<LOL I tried to convince my husband that the RO/DI filter was for our drinking water too. He wasn't so convinced, but some people do buy RO/DI filters for their own drinking water.>
I know that they are recommended but could I get by without one until I decided to add the corals and anemone?
<You could get by without one for just fish. However, you'll want to have all RO/DI water before you even think about corals and anemones. You could also buy RO/DI water from your LFS.>
Would it cause any harm to the live rock and sand? Or any livestock I may get including snails and small hermit crabs?
<It's hard to say generally. It just depends on how bad your tap water is and how sensitive the animal is. At the very least, try to get some kind of water filter. Even just a cheap 2 stage RO filter would help.>
I apologize if these are asinine questions but I'd like to make sure I do this right.
<No problem. Keep researching/reading.>
Thank you in advance for your response.
<Best,
Sara M.>

RO Water and Ammonia...    9/11/07 
Hello once again! I must thank you all for this great site and all the help you guys do for us, the average aquarium hobbyist!
<:-)>
My problem this month... hahah... lies within the Ro water I am using. I buy it locally from a grocery store bottled, its says on the label processed by reverse osmosis. Whenever I mix up a fresh batch of saltwater I always seem to get a reading of Ammonia at 0.3-0.5 Mg/L.
<yuck>
I wrote the wonderful people at Coralife and they said RO does not remove Ammonium Ions in the water column, and when you add the salt, the salt brings out the Ammonia readings. I use Hagen/Nutrafin test kits for everything and have confidence in their accuracy. The guy I spoke to said to use Zeolite before adding in salt,
<?!?>
it only works in freshwater.
<Hmmm, yes, this is what sewage treatment plants do. But they have specialized zeolithic filters that aren't commonly used by aquarists. There is a product line manufactured by Zeovit which incorporates some kind (unknown) zeolite material in marine aquarium filtration. But this is not for treating pre-mixed water or water for water changes/top offs.>
I have a 20g Rubbermaid bin for mixing up water, with a powerhead and heater as well. What do you guys think I should do? 1. Use the Zeolite in a small power filter, before adding my salt?
<I suppose this could work if this zeolite material is the kind that removes ammonia. What a lot of people don't understand is that "zeolite" is just a general term for any of at least hundreds of different kinds of porous rock. Some zeolite rocks/powder will remove ammonia, some won't.>
If so, how long? 24hrs? 2. Buy a RO/DI 3 stage filtration setup?
<This would be my suggestion. Most "serious" reef aquarists have their own RO/DI filters or at least purchase RO/DI filtered water from a LFS.>
Will I still get some ammonium ions in my water from using a RO/DI unit??
<If it's working properly, no. RO/DI filters produce water that's pretty much as close to distilled water as you can get. When I use my RO/DI unit, I get a TDS reading of 0.>
Thank you for you help in this matter! It is greatly appreciated.
<De nada>
55g reef tank, 55lbs LS, 60 lbs LR, 3 powerheads, Aqua C Remora skimmer w/ surface skimmer box. 1 yellow wrasse, Organ pipe coral, 1 skunk cleaner, 2 peppermints, 10 scarlet hermits, 10 Nassarius, 5 red legged hermits.
Brad Ketner
<Sara M.>

RO/DI question  8/20/07
Just finished your impressive array of FAQ's about RO/DI and other water conditioning. I am starting a 120g reef tank.
<Just finished my first cup of Joe... am getting up for a refill>
I am hoping that you can help me determine whether a RO or DI or a combination is needed in my case. I want to make sure I provide a good environment for my creatures.
<Sounds good>
I got a water report done by my water company the contaminants are as follows
Barium ppm 0.063
Fluoride ppm 0.86
Lead ppb 3
Nitrate ppm 0.113
Sodium ppm 14.4
Chlorine ppm 1.9
Trihalomethanes ppb 73
<Want to take care of these last two...>
Haloacetic Acid ppb 46
Bromate ppb 13
Copper ppm 0.77
<Mmm, likely will complex with synthetic mix...>
Thank you so much for your help in advance.
<Is there a question here? Are you a strong candidate for RO? RO/DI? Might be... From what is presented, I would just use reverse osmosis... and pre-mix, store new water for a week ahead of use... as proscribed on WWM. Bob Fenner>

Re: RO/DI question  8/21/07
Thank you for your input, based on reviews on the Spectrapure setup from your website I am looking at two different models one is $200 and the other $300, both 60GPD. Will the lesser expensive of the two meet my needs for a reef aquarium. Below are the specs and the filter particle sizes. Thanks alot.
<Bob answered the last question recommending R.O. unit. I am a fan of RO/DI for reef tanks. I advocate 0 TDS readings for best results. D.I. unit is required to get that low.>
the $200 model is spec.ed
Maxpure MPDI
SEDIMENT FILTER (SF-MT-1-10)
CARBON BLOCK (CF-1-10)
RO MEMBRANE (MEM 25-180) *
DI CARTRIDGE (DI-SB-CI-10)
SpectraPure ® MaxPure T MPDI Systems incorporate high-flow high-rejection TFC membranes, a 1 micron sediment filter, a 10 micron carbon block filter, and a custom formulated 10"color-change DI cartridge. MPDI systems are available from 25 to 180 GPD (95 to 680 LPD) production rate, and come with a 3/4" garden hose adapter.
the $300 model is spec.ed
Maxpure CSPDI
SEDIMENT FILTER (SF-MT-0.5-10)
CARBON BLOCK (CF-0.5-10)
RO MEMBRANE (MEM S 25-180)*
DI CARTRIDGE (DI-SB-10)
SpectraPure ® CSP-DI Systems feature SpectraSelect T TFC membranes (guaranteed >98% rejection), a 0.5 µm MicroTec T sediment filter, and a 0.5 µm Carbon Block Pre-Filter (for greatly enhanced membrane life), plus a 33% larger capacity SilicaBuster T 10" DI cartridge. The standard pressure gauge and clear filter housings mean better visibility to system performance. Also included is a filter wrench and a 3/4" garden hose adapter.
<These are all fine units. I would recommend a 6 stage unit from the www.thefilterguys.biz/ OCEAN REEF + 2 SIX STAGE 75 GPD RO/DI>
<Rich aka Mr. firemouth>

Re: H2O Purifiers 8/1/07
Thank you for your quick response James.
<You're welcome.>
I live in the suburbs of Boston.
Should increasing the contact time still not solve the problem, will DI help?
<Deionization generally just removes heavy metals, calcium, magnesium, and salt.
I do not believe it is going to do much for phosphate removal. An R/O unit would have been a better choice for your application, as this will produce the purest form of water. When R/O is used in conjunction with a DI unit, you will have produced a very pure end product. James (Salty Dog)>
Regards,
Kim

RO/DI...Recommendation, check eBay  7/20/07
Crew,
<Hi Andy, Mich here.>
Not a question, just some info for those looking for a good deal on a RO/DI unit.
<Always appreciated.>
I did a lot of research on units and about the cheapest I could find was a pretty basic unit for $150. Most etailers I looked at sell the 3 and 4 stage units for $200+. Before I bit the bullet, I remembered that it had been a long time since I bought anything on eBay, so I decided to do a quick search for RO/DI units. Well, I just took possession of a new 100 gpd "Zero ppm" 6 stage RO/DI unit that I bought on eBay for $76 (plus $28 shipping), and the thing works like a champ! My TDS went from 116 to 0. The seller offers various configurations for different prices.
<Thank you for this recommendation and reminder. Others will benefit and appreciate. Mich>
Andy

Thoughts on this RO-DI Unit 6/10/07
Hi Crew,
<Andy>
Do you have any thoughts/experience with Melev's Reefkeeper, a RO/DI unit that sells for $169 plus shipping (http://www.melevsreef.com/ro_di.html)? I've been researching units, and this price seems too good to be true. I found references to this website on WWM but not specifically to this product.
Thanks
<Have met this fellow and he is the "real thing"... I suspect this is a fine unit... About what it really should cost. Bob Fenner>

Reverse Osmosis 6/4/07
Can you recommend a good RO unit? I'm looking at a Costco version but wondering of this is same as a RO/Di unit? What’s the difference?
Thanx for your response
Ace
<The difference between an RO and RODI is the RODI has an extra stage to remove what little material makes it through the RO membrane. As to whether you need it or not, that depends on your source water. Most RO and RODIs are pretty comparable based on gallons per day, personally I love www.airwaterice.com for their customer service.>
<Chris>

RO w/o DI - 5/29/07
Hey Crew,
<Dave!>
I have looked and looked everywhere I can think of but can not find the answer to my question. I have been reefing it up for about 6 months now and decided to buy a RO/DI filtration system to make the water healthier for my tank. I went to Home Depot and started looking around and the only ones I found were Reverse Osmosis systems without the deionization. <Yes, the units for drinking water don’t need to polish the water as perfectly as we like for our reefs.> Nobody seems to have an answer on if the deionization is the part that I need. <It just finishes removing what the RO misses. RO takes out a good bit of junk, but can’t get it all. The DI is very thorough, but too expensive to use to clean up all the junk out of the water.> Also it did not mention removal of phosphates on any of the packaging, So I started wondering if possibly the word Phosphate is a generic term for several different things. <No, that is one specific thing, and it happens to make algae grow like crazy.> I did in the end buy a system and it does remove all sorts of things but still no mentioning of phosphates. I guess a chemistry class may be in order. <Heee! Reef-keeping Chemistry 101. If you are not having a problem with phosphates (easy to test source water for) then I wouldn’t worry about them. But it should be fairly straightforward to add a DI unit to the back end of your RO system. A simple DI cartridge (or two) should finish removing anything the RO misses.
Read here: http://www.wetwebmedia.com/rofaqs.htm >
Any help is appreciated, and for the record I started reading on your website a few days into getting started on my reef tank and have been very successful because of it. <Glad to hear!> Also I really want to check out some of the books you guys have out. Can you steer me in the right direction on where to find them, and the names? I can’t find the page I found them on before.
<Links here to several dealers that carry Bob's and Anthony's books:
http://www.wetwebmedia.com/WWMAdminSubWebIndex/dealers_and_distributors.htm
I bought “Conscientious Marine Aquarist” at a LFS, and ordered “Reef Invertebrates” from MarineDepot.com. >
Thanks again
Dave
<Welcome, Alex>

RO, DI, or RO/DI? - 03/12/07
Hello
<<Good evening Pam>>
I've been reading your FAQ's about RO/DI's.  I've read positives and negatives on all 3... RO, RO/DI and DI only.
<<Indeed, like most all aspects of the hobby...is subject to much opinion.  But even so, I think there are some basic guidelines that can help "you" with your decision>>
Some on WWM say RO is a waste because it wastes such a huge amount of water and you should do DI only.
<<Mmm...nothing wrong with being "green," but it can be taken to the extreme I think.  Everything has a price, and in my opinion/my locale, the waste water created is worth it to me to operate an RO filter versus alternative methods to filter water for the benefit of my reef.  But if this "waste" is something that you can't/won't tolerate, one can find ways to utilize the waste water...from diverting it to your garden to using it to wash your clothes>>
Some say RO is all that you need and DI is unnecessary.
<<In some instances, yes.  For a FO or FOWLR system this is often the case.  However, REEF systems often will benefit from the extra "purity" a DI cartridge can provide>>
Some say RO/DI is the only way to go.
<<If you want what is generally considered the "ultimate" in purity, yes>>
I talked to two guys at my LFS, and one said to have my water tested, and I may only need a RO unit.
<<Good advice...depending on your system>>
The manager at the same LFS, said for only $50 more, it would be crazy not to get the RO/DI.
<<Arguably this too is good advice>>
I haven't had my tap water tested.  I have city water and a 53 gallon tank that I just bought.  Confused on what I should buy.  Everyone seems to have a different opinion.  Help!  :)
<<Personally, I prefer a combination RO/DI unit for "any" marine system, but hopefully you are gaining enough information to make your own decision>>
Thanks, Pam
<<Quite welcome...happy to share.  EricR>>

Re: RO, DI, or RO/DI? - 03/12/07
Thank you Eric.
<<Quite welcome Pam>>
I was leaning towards RO/DI....and you helped convince me that's the wisest decision.
<<Excellent>>
This hobby is soooooo expensive...that it's not worth chancing trying to filter with RO only or DI only.
<<Have their places as separate entities...but as I stated, I prefer to use them in combination>>
Thanks again.  You guys are the best!!
Pam
<<We do try [grin].  Eric Russell>>

RO vs. Distilled 2/02/07
Crew,
<Celeste.>
Quick question.  
<Answers to follow suit.>
Our water is very hard.  We've been working on trying to lower it by mixing our filtered water (using an Ecoquest living water system that removes the bad stuff but leaves all the minerals, etc. in) with RO water that we've gotten from the store.  
<?>
We wanted to make sure it lowered the hardness before investing in an RO unit.  After a week or two, we tested it, and our hardness hadn't dropped at all.  
<Not exactly clear on the methodology being used here. It sounds like you take RO water, and then mix at an unspecified ratio with water from a drinking water filter. I wouldn't bet on the repeatability of the results with these "trials" in water chemistry. Furthermore, the RO that the store is using may be long overdue for a cartridge replacement. >
We tested the RO water, and it's at 11!  
<RO doesn't remove everything, but should be a lot softer than that compared to your tap-water.> <<Should be much softer than this... RMF>>
Not soft at all.  (Our filtered tap water is 13.)  We've been using distilled water and it's dropped it down quite a bit.  I've been researching and getting confusing information on
whether RO in itself is soft or if it depends on your tap water to begin with or whether the store we were getting the water from just never changed the filters or something.  
<http://www.wetwebmedia.com/ca/volume_2/cav2i4/RO_systems/reverse_osmosis.htm>
If we bought a RO/DI unit, would it soften the water, or should we look into getting a distiller that leaves the water extremely soft?  
<The expense of distilled water is prohibitive, IMO. RO/DI in a five-stage configuration will leave extremely soft water.>
Thanks again, and I'm sorry if this is answered somewhere.  We really appreciate all the help with our tanks: articles, FAQs, and answering our questions.
<Not to worry, Celeste.
Good luck!
-GrahamT>
Celeste

DI vs. RODI in NYC   11/30/06
Hello,
<Hey Dylan, JustinN with you today.>
There are many informative responses to the FAQs on your sites RODI page. Thank you for those!
<You're welcome, from all of us>
I am still wondering if I can get away with using only a DI unit in New York City. The water here is very good for drinking, but I live in an older building and know nothing about the state of the pipes.
Furthermore, I am concerned that if I don't spend the extra cash now for a RODI unit and instead just use the DI unit, I will pay in the end when something goes wrong in the tank. (Yes, I know that might be a little dramatic). I am new to this hobby...this is my first reef setup as an adult after a childhood of watching and helping my dad...so I would like to make it as smooth a start-up as possible.  
Any advice will be greatly appreciated.
Thank you,
Dylan
<Likely you would be fine with either an RO-only unit, or a DI-only unit, but given the choice of the 2, I would choose the RO. Replacement parts and filters are usually cheaper than large quantities of DI resins. No worries though, either should serve your purpose well. Hope this helps! -JustinN>

Re: DI vs. RODI in NYC   12/1/06
Justin,
It's either a RO/DI or just a DI. How could they both do the same thing or produce an equal end product? Why should I use the RODI versus just the DI, other than price, for the water for my reef tank?
Thanks,
Dylan
<Well Dylan, both outputs of <sic> deionization is extremely pure water, the difference is that an RO/DI unit will not extinguish your deionization resin as quickly as a DI unit alone, because of the initial level of cleansing handled by the RO unit. Beyond this, functionally they will be very much the same. Either will work here. Cheers! -JustinN>

RO Units...Which One?, What Configuration? - 09/06/06
Hi Crew,
<<Hello!>>
Thanks for taking my e-mail today.
<<Welcome>>
I have finally decided to buy my own RO Unit to supply my 75 gallon reef tank.
<<Cool!>>
I was looking at a few different units and was wondering if you could help me clarify a few things.
<<Ok>>
First off, I live in Saint Paul, MN and my water comes from the Mississippi.
<<Via a water treatment facility I hope>>
Second, I live in a 100 year old house and I assume some of the plumbing is fairly old.
<<Mmm, a fair assumption...>
I was looking at the Kent Marine Hi-S and Maxxima Units as well as the Pinnacle + Units.
<<You might also want to peruse what is available at your local home center (Lowe's, Home Depot, etc.).  All RO units operate on the same principle, and the membranes used by all are made by just a few manufacturers...you might find you can save some considerable cash by buying/configuring your own unit from other than a retail "fish" outlet>>
My first question is if you know the difference between the Hi-S membranes and the TFC membranes (i.e. is the Hi-S as good at removing things other than silicates?).
<<Not aware first-hand, but would assume as much.  A search of the NET should find rejection-rate tables re that will allow you to make comparisons, but unless you "know" you have high silicates/have a silicate problem you probably don't need to spend the money for the Hi-S membrane>>
Secondly, with my water source, would you recommend getting the Pinnacle because it has two carbon pre-filters?
<<I prefer "two" carbon cartridges on my system for the extra "capacity" provided.  My recommendation here is to utilize the "solid block" carbon filters with "micron ratings" for particulate removal (5-micron for the first stage...1-micron for the second).  Periodically removing and rinsing under the tap will extend their utility>>
Third, if I get the Pinnacle would you recommend hooking up a DI filter inline?
<<Indeed...as the last stage of the filter.  Another money saver here is to purchase a "refillable" cartridge and buy "bulk" resin from someplace like Resin Depot (ResinDepot.com).  Initial cost more, but you'll save about 75% or more (depending on how much you pay for the "disposable" resin cartridges) over the long term>>
Also, I was planning on hooking up the RO Unit under my kitchen sink.  Can I run the unit from my cold water source or do I need it to be temperature controlled?
<<The units operate more efficiently when the water temperature is above 70F (my unit's output doubles during the hot summer months due to an increase in source water temperatures), but trying to regulate this is likely more trouble than it's worth, and you certainly don't want to hook the unit up to your hot water line...just plumb to your cold water source>>
Do you have any tips on hooking it up under my sink?  
<<Nothing special, merely follow the manufacturers instructions.  A keyword search on the NET also yields much info re>>   
Thanks very much for the help,
Tim
<<Is my pleasure to assist.  Regards, EricR>>

Which RO Unit? - 09/30/06
Hi,
<<Hello>>
I was wondering if any has used any of these products, Coralife Pure-Flo II RO unit or Seachem pinnacle 35 gpd RO units?
<<Afraid not>>
The reason I need a RO unit is because my tap water is very hard (300)with a very high pH (8.4), and I want to keep fish that require a low pH and soft water.
<<I see>>
Are either of these systems any good or would you recommend a different brand.
<<Either will work fine.  All these units operate on the same principles...you could even obtain a (cheaper) unit from someplace like Lowe's or Home Depot>>
Thanks, this is the best website for fish info and advice I've ever been on.
--Sbatiste
<<We're pleased you find it useful.  EricR>>

- Kitchen Water Filters -
Can you use sink water filters for saltwater changes. Having lots of problems with diatoms in the last 4-5 weeks. My tank has been up since Oct and never had a problem till now. I have been using the tap water from the first. Now I'm getting this algae. I have a Brita filter on the sink and thought it would take the chem.s out. <Would certainly take out the chlor-ines/amines... would mean you'd need to change the filter cartridge more often.> I do water changes every other week but been doing them more often since this is going on. I use the conditioner to take out the chlorine and such and use instant ocean. I've read about the other filters to use but so expensive. I thought about the Brita on the faucet. <Will take out some stuff, but not all... not diatoms.> Please let me know thank you.
<Cheers, J -- >

Kati Ani deionizers... DIY units 9/20/04
Anthony,
I know you like the Kati  & Ani units for water purification.
<yep been using them for over 10 years>
I am trying to locate a Kati & Ani 2 but am having no luck. Dr. Fosters only have the Kati 10 but have the Ani 2. I did a search on Google but couldn't find anyone else that sells the Kati & Ani units. Any ideas? Thanks Pat
<no worries... better still is the bulk resin for DIY canisters or Kati Ani replacement. Spectra-pure sells them at:
http://www.spectrapure.com/St_replac_p5.htm
best of luck, Anthony>

RO/DI or Kold Ster-il 9/8/04
Thanks, Bob -
<Anthony Calfo in his stead>
I guess I'd also like your opinion as to the quality of water produced by the Kold Ster-il vs. the RO units, please.
Dave Parker
<hard to compare... apples and oranges really. Kold Ster-il produces highly filtered water... but does not demineralize like RO or DI. Some people have decent tap water with desirable mineral content... just in need of cleaning up some of the nasties (chlorine, phosphate, etc). For such situations... Kold Ster-il is excellent. But for worse source water (quality or variability of composition) or for aquarists that simply want better control over the water used/produced... then demineralizing and then buffering back up (with desirable elements of hardness) is the way to go vis a vis RO or DI. I personally favor DI as there is no waste water produced and the recharge chemicals are dirt cheap and be neutralized to inert so to speak. RO instead wastes a lot of water with even expensive units and the cartridges are an ongoing and considerable maintenance expense. Best regards, Anthony>

RO/DI or Kold Ster-il 9/8/04
Thanks, Anthony,
<always welcome :)>
If I understand, I can produce top-quality water, then using a Kold Ster-il followed by and add-on DI stage, and produce no waste water.  Is this correct?
<hmmm... my apologies. I may not have been clear. The first thing you need to decide on is whether you need ultra pure (ala distilled) water from an RO or DI that you are willing to NEED to aerate and buffer before every use. This is the most work on your part, but produces the most reliable, clean water for evap top off or for salting for marine use. But it is dangerous to use raw untreated (unbuffered) DI or RO (or distilled) water. Yet... this is what many aquarists choose to do, myself included, to insure superb source water. Kold Ster-il units on the other hand do not demineralize water but leave in Calcium, Magnesium, etc. They are basically top shelf chemical filters that clean up the water quite a bit... but do not reduce the conductivity/hardness, etc. It is an outstanding prefilter for a DI... and if your tap water is not too bad... can stand alone without even needing a DI or RO. DO test your tap water to see how bad is bad first. Ultimately, the Kold Ster-il  + DI units an excellent choice in my opinion>
thanks for bearing with me, Dave
<no worries. Anthony>

RO/DI or Kold Ster-il II 9/8/04
Thanks again, Anthony,
<cheers again>
I always aerate and buffer with SeaChem Marine buffer before adding my salt - I happen to use Oceanic if it matters.  I understand about not using distilled or raw, RO/DI as top-off - heck I don't even do this for my goldfish tank.  I'm simply looking for a way to produce top-quality water for this process without wasting 4x what I produce,
<ahhh... definitely DI then for you>
and to be able to produce it more on-demand since no one is home during the day to watch the RO unit overflow my Rubbermaid cans.
<no worries... you will have this with DI. But with either... there is always a simple float switch for your reservoir>
I have a whole-house water softener, so that much waste water gets expensive, and I believe (correct me if I am wrong) that my water softener will take a lot of the calcium and magnesium, in particular, out, but leave some sodium (or in my case, potassium) in.  
<yes... true. Salt softeners are NOT recommended for use with aquatic life. Long term problems with water quality>
Do I need ultra pure?  Well, I get algae blooms like crazy using tap, that is why I started hauling RO from my LFS. So I guess I may not have been clear, either - I want to produce top-quality raw water, with as little waste as possible, and am in the practice of buffering and aerating and buffering already. To ask the question another way, what am I likely to leave in my water by using Softener -> Kold Ster-il -> DI stage vs. having an RO unit in the middle, and is this difference enough to cause problems down the road.
<just use the Kold Ster-il & DI stages... never the salt softener>
Appreciate the help and advice, Dave
<best of luck, Anthony>

RO/DI or Kold Ster-il
Hi, Gang and thanks for a great service!  I am setting up a new 120gal FOWLR, and am getting tired of hauling RO water from the LFS.
<I hear you... my arms are a good inch longer from hauling water about all these years>
I'm ready to put in a system myself.  However, I am scared by all of the waste water the typical RO/DI units produce, as water is not cheap here.
<Mmm, I divert the "waste line water" to my pond outside, and in turn to the garden>
I've heard about this Kold Ster-il unit, and that it does not produce wastewater.  Can you help me understand the difference in the processes, and perhaps suggest which might work best?
<This unit uses filtrants that are not re-used... contactors... so all water that is filtered, passes through the unit is used. RO utilizes selective membranes capitalizing on ambient or increased pressure to "squeeze" water molecules and exclude solids (and their zones of hydration) and some other liquids, gasses from getting through the membrane... with their water periodically bypassed to waste>
Either system would come after my water softener, and in this, I use potassium chloride rather than sodium chloride as the agent to wash/renew my resin bed.  Thank you for your input!
Dave
<The real (IMO of course) difference in practical terms are the upfront costs of the two types of units/technologies, versus the amounts of waste water generated... Both will produce high(er) quality water of use. If it bothers you to "throw away" so much RO waste water (a ration of 4-5 to 1 of usable is not uncommon) than I would go the contactor route. In all fairness though, do take a look at your water bill, see how much water is going for other uses... Bob Fenner>

Finding a 2-column Deionizer 11/8/04
Anthony, I am trying to decide on a RO/DI product. You said to look into a 2-column deionizer as a possible choice. I have not been able to locate a manufacturer or distributor for this.     
Do you or can you give me a short list/recommendations for these?. Thanks Keith                                                             
<a simple keyword/phrase search on google for "deionizer, aquarium" and like entries will yield good leads my friend. Any of the big mail order companies too carry deionizers: Marine Depot, Custom Aquatic, Drs. F&S, etc. The brand I have used for years is "Kati Ani" from Germany. Anthony>

Google, Google, Google till it hurts! Kati Ani dealer 11/9/04
Hello All!!
<howdy>
Anthony, in response to a deionization question yesterday you mentioned that you personally use the brand Kati Ani from Germany.  Are you referring to Kati Ani generically or is that the actual brand name.  I asked because I have seen many other recommendations on this product before but cannot find a distributor or a manufacturer's website.  I believe it is made by AquaTech, but I cannot fine their website.  If you have any info to point me in the right direction I would be quite appreciative.
Thank you kindly, Corey
<my apologies for the title to this e-mail, my friend... but I am rather frustrated today - feeling like an enabler - with friends/queries from folks with seemingly little effort to do a simple keyword search to help themselves <sigh>. To help you and illustrate a point... in response to your question, I simply went to the google search tool which is plastered all over our website and well known at large. I typed in "Kati Ani price" (three common words that would appear on a page with this product if it existed out there somewhere)... and the very first page that came up has a link to:
http://www.drsfostersmith.com/product/prod_display.cfm?pcatid=4499&N=2004+22789
ironically... this merchant is also an advertiser. Our only advertiser on WWM at present: Drs Foster and Smith/LiveAquaria.com
I'm sure there are other merchant of this product out there... google till it hurts, bro. Anthony :)>

- RO/DI Evaluation -
I bought this unit and will be receiving it tomorrow, I have found 1 previous post about this unit. It is mfg. Water General and it's cost is minimal, it is a six stage unit will you please evaluate and let me know what you think of this unit in comparison to a SpectraPure or Kent Marine.  
http://www.watergeneral.com/support/html/RD100.htm
<I'm afraid there just isn't enough information there to form an opinion. Most RO/DI units are very similar and vary mostly in configuration from manufacturer to manufacturer. The parts used in each are for most intents and purposes identical. I'm sure this unit will treat you fine.
Cheers, J -- >

- RO/DI Evaluation, Follow-up -
the question was about the rejection rate in the other post. <I don't see any information there about rejection rate, but four to five times the output volume is not unusual.> But I am just curious if this unit is going to give me quality water for a reef tank. <I'm sure it will be fine. Cheers, J -- >

- Distilled vs. RO -
Hi gang,
<Good morning, JasonC here...>
The plethora of information contained in WWM always astounds me... keep up the great work! <Ok.>
I'm presently using a distiller for my aquariums... it's small, uses about 750W of power, and takes about 3 hours to make 3 quarts or so of distilled water. <Not a very efficient way of producing water for your tank.>
I've been considering installing an RO system, but know the membranes, pre-filters and DI canisters are rather costly. <Not as costly as your electric bill...>  Has there been any cost studies on RO water -vs.- Distilled? <I think you and I just did one... at this rate, you can buy new membranes, which last for years when flushed with the money you save from not running your distiller.> I know the RO system would be far more convenient... BUT... I can live with the distiller for about $10/month!  <An RO filter would produce much more filtered water per dollar than your distiller.>
FYI- Our tap water is quite hard, 30 or more dKH, high in nitrates and high in particulate matter...JOY, huh? <Just order a back-flush kit to go with the RO device and the membrane will last a good long time.>
Any information and/or experiences on this would greatly be appreciated!
Cheers,
Michael
<Cheers, J -- >

DI Water 7/13/03
Hi.  I have a question about treating tap water using a DI unit.  What all does DI remove and what will it do to the water in terms of pH and hardness?  
<it varies by resin brand/quality... but better units almost completely demineralize water (zero hardness). pH will likely be acidic or at least unstable for the lack of buffers. It needs to be aerated and then re-mineralized slightly before use. There really are many FAQs and information on this subject in our archives at www.wetwebmedia.com  Do a keyword search on the subject with the Google search tool at the bottom of the homepage>
Kent and some of the other manufacturers are less-then-clear about what exactly their units might and might not take out and how it will change the water's chemistry.  
<just one of the many reasons why I do not use or recommend Kent products specifically. I have been quoted as having said that I would not take their products for free>
I am considering purchasing a unit to help combat tap water that is less-then-ideal for my reef tank and a possible Discus tank that I may be setting up in the next few months.  
<excellent and agreed... do look at the Kati Ani brand (Dr.s Foster and Smith, Gwynnbrook Farms, etc). I have been using this brand for over 10 years [in my discus hatchery and an industrial sized one for my coral farm/greenhouse]>
Will DI water be beneficial, and is it better then RO
<I think so as many do... arguably produces slightly purer water>
(I don't like the idea of how wasteful RO seems to be)?
<agreed!>
Thanks! Christopher
<best regards, Anthony>

- Dealing with Marine Velvet & RO/DI Clarification -
Thank you for your prompt reply to my previous question on Marine velvet.  My Cuban Hog , Flame hawk and Zebra Moray Eel have all survived the attack of Marine Velvet.  The Cuban and Flame hawk are eating well and swimming normally.  I am planning on not adding any other fish to my 200 gallon tank for the next 6-8 weeks to break the cycle of this parasite. 
<You won't accomplish much as long as there are fish hosts in the tank.> 
My question is can I keep these three in the main tank. 
<No, they should be in individual quarantine while you let the tank go fallow, also chance to treat the fish apart from the tank if something were to reoccur.> 
I know you've said that the tank has to remain fallow without any fish to break the cycle. 
<Heh... I just said it again ;-) > 
I'm wondering if the Flame hawk and Cuban Hog have developed some immunity to the Marine Velvet which would allow them to stay in the main tank. 
<Fish that are in excellent health can fend it off to some extent, but I'm going to guess that your fish are under some extra stress, given that you used the phrase 'survived the attack' - I would guess you will see the velvet again.> 
Would a UV aid in minimizing the outbreak of these and other pathogens. 
<Only to a very small extent... I don't really endorse the use of these unless of a hospital system. Can do without UV by careful use of quarantine.>
My second question is about Reverse Osmosis.  My LFS is using a two stage system when he is making water for his tank. He does not use the reverse osmosis stage to filter out his water - just the prefilter and carbon filter.  Is this adequate or should I do the reverse osmosis to ensure the water is clear of any contaminants. 
<Depends one what those contaminants are - how is the quality of your tap water? Could be particle and carbon filtration are all you need.> 
How does this compare to a DI ( which I am assuming is a deionizer). 
<Each is a type of filtration so each is particularly good at filtering out certain 'stuff'.> 
The only deionizer I've seen in my area is TapPure which makes about 25 gallons before the cartridge is replaced. 
<Not very economical.> 
What do you suggest? 
<Well, in RO/DI, the deionizer is the last stage in the filter so the resins last a little longer, but is the nature of all cartridges. Unless your tap water is bunk, you can probably just use that. Please read here:  http://www.wetwebmedia.com/water4maruse.htm >
Thanking you in advance  Vito
<Cheers, J -- >

- RO/DI and Water Purification -
Hi,
I've been reading all of your articles on water purification and it appears it would be wise to invest in an RO/DI unit. <Really depends on the quality of your source water, but for the most part these are a worthwhile investment.> I've been looking online at the Kent, Captive Purity and Spectrapure units.  The price of the high end SpectraPure unit is about twice that of the other two.  Is there any reason for the large gap? <To be honest, I don't know why the large price gap - could be the parts or cartridges they use. Am aware of high-volume systems that are quite pricey, but worth it if you need the output.> Also, can you recommend a good unit. <I'd go with the Captive Purity [which is what I own] or the Spectrapure just because I have an allergic reaction to Kent products. But really for the most part, almost all RO/DI units are created equal - same parts, same cartridges.> I don't mind paying a little more as long as I only buy it once.
Thanks for your feedback
-Brent
<Cheers, J -- >

- RO Selection -
I'm in the market for a r/o filtration system.  Do you have any you recommend?
<They are really are pretty much the same. Find a unit that fits your price range and you'll do just fine. Cheers, J -- >

RO (devices for sale)
 Bob,
I saw some references to RO in your forums/posts and wanted to offer my systems as an option. There are a lot of systems out there, some good some bad, but you never know what you're getting. My systems are made in the US with US components (no third tier foreign copies) and are FDA/NSF approved. The price is right and I have addressed all the normal concerns of RO: low pressure in tank, wasting too much water, slow production and limited capacity (small tank that isn't full). My systems are a minimum of 5 stages (4 stage and lower increase membrane fouling and have lower quality water) produce 50 gpd - five times faster than most RO systems (they are rated 100 gpd but that isn't accurate, although most suppliers go with the rated gpd) they waste 400% less water than other systems, fill the tank to 90% of line pressure (competitors go up to 70% - 60psi X 70%=42psi in the tank) and produce great water and only cost $700 if installed by the customer.
<Very nice specifications, but the price a bit steep for the vast majority of pet-fish enthusiasts... however there is (IMO of course) a percentage of "higher end" folks (maybe a handful %) that would pay for such units>
I generally sell large upgraded tanks to aquarium owners 10 - 50 gal or more. I have larger systems as well from 50 gpd to 10,000 gpd. I also sell a distiller/ozonator that cleans up several problems in fish tanks. Email me and I'll send you a sample of the water you can put in a tank that has problems and you'll see the difference.
<No need/desire to send sample. I don't have equipment for testing such. Please send along your URL and we'll post it on WWM and give you what feedback we can to assist you in marketing your products. Bob Fenner>
Thanks,
Tim Krusemark
Aquatek Water Treatment

- RO & Circulation Questions -
Jason,
<Good n'you?>
Thank you very much for your response. <My pleasure.> It helped greatly. <Even better!> As it turns out, I found that the HD/Lowe's RO units are more costly than ones I can order on line from aquarium supply stores (I think due to the mandatory storage tanks and fancy chrome faucets that come with them).  As a result, I will wind up getting a 25 G model that should easily allow me to follow your advice on filling the new tank over a few days.
I hate to be a pest, but I have 1 additional question (for now ;-)).  I just read Anthony's article "water flow, how much is enough", and what I'm unclear on, is when he says that most keepers of corals advocate 10-20 times the tank volume per hour, is this the total between everything including power heads? <Yes.> Or does that 10-20 spec just take the main system pump into account? <Total system circulation, including powerheads.>
Thanks again for your advice.
Eric
<Cheers, J -- >

Cheap RO/DI...
Found this link on another board gang, for those looking for RO units, these prices seem very attractive, don't know if anyone has used these guys but thought I'd pass it along....riot.....
http://www.airwaterice.com/Retail%20Price%20List.htm
<Very reasonable pricing. Thank you for sending this along. Bob Fenner>

- RO/DI Filters -
Hi Mr. Calfo and  Bob and Steve and the rest, <Greetings, JasonC here...>
I want to buy me an ro/di unit(4 stage). I am not familiarized w/ them that much, although I have done my homework and I learned that they are 3 different types of membranes: TFC, CTA, and Hi-S, the latest one being of the highest quality. I am now wondering if there's a substantial difference on water quality if I buy a unit that comes w/ TFC instead of the HI-S ones, remember that I will have a 4 stage. <I don't think so in a 4 stage unit... the DI would get most everything the RO missed, which wouldn't be much. In my opinion, the biggest differentiator in RO/DI units is the flow rate - total gallons per day produced.> I want to know if it makes a difference who makes the membranes?? (film tech vs. Kent) <Probably not... I'd be willing to bet Kent doesn't manufacture their own RO membranes but simply repackages them.> Is the membrane size standard from different brands? <That I don't know.> what about the canister size?? are they standard?? <Seem to be.> and what If I get a unit that comes w/ TFC can I use them and then replace them w/HI-S? <Yes.> can I use membranes that are for a 35gpd unit into a 36gpd?? <Yes.> I want to support my LFS and he offered me a 4 stage 36gpd for $165.00, TFC membranes (brand new), but do you think I should go ahead and buy another one? <Why not go for it and test the outgoing water - I'm sure it will be 'good enough' as they say.> (have suggestions??). I want to use the unit for top off and water changes for my 75g full blown mixed reef. Are the pre-filters sediment and such) and the block carbon filters necessary/do I see a difference?? <If you want the RO membrane to last any period of time, they are quite necessary.> I'm sorry... lots of questions I know! Thank you so much for any help you can give me though... I just want the best for my Tank!!
YOUR WEB SITE IS THE ONLY ONE !!(the best)
<Cheers, J -- >

Water filters
Bob or Anthony: I want to know what your opinion is on Poly-Bio Marines KOLD STER-IL water filter.
<outstanding>
There sales pitch make it sound better than R-O units in many ways.
<agreed>
Will these units give me very good quality water?
<some of the purest>
Currently use Kati and Ani but recharging is a pain.
<heehee... a deionizer is my strong preference for minimizing water waste actually>
Any info or input would be much appreciated. Thank you very much:
Pat
<either produce very pure water. Best regards! Anthony>

- Using RO/DI -
Hi how are you today?
<I am well, thanks for asking.>
I am setting up a 55 gal. reef tank and question the need for a RO or RO/DI unit. I just received a copy of the water quality in my town. It list some 10 substances and the highest detected levels of each from 1999 thru 2001. They are as follows.
Fluoride 1.4 ppm
Nitrate 4.9 ppm
Alpha Emitters 12.0+/-4.0 pCi/I
Copper 1,000 ppb
Lead 7 ppb
Bromodichloro-methane 0.8ppb
Chloroform 3.4 ppb
Sodium 25.9 ppm
Sulfate 36.9 ppm
P-Dicholro-bensine 0.4 ppb
(ppm = parts per million  ppb= parts per billion)
Looking at these findings do you think an RO or RO/DI unit is advisable or necessary? <I would use it.> If so what are your thoughts on the KENT HI-S 60GPD MAXIMA RO/DI unit as I can get this unit at a very good price at Champion lighting. <Most all RO/DI units are created equal, with the price differentiator being the output.>
Thanks as always
Dennis
<Cheers, J -- >

- RO/DI at Home Depot -
Am I missing something? I have been reading all the FAQ re. RO system an keep reading about the simple and cheep RO system at home Depot. I have gone to there site an find the GE Reverse Osmosis Filtration System
Model: #GXRV10ABL to be the only RO system they have. It produces 10 gal per. day and cost $239.00 I can purchase the KENT HI-S 60GPD MAXIMA RO/DI unit as noted below for $206.00 and it does 60 gal. per. day and also has the DI unit and HI-S membrane. What am I missing? <Probably nothing - not all Home Depots are merchandised the same. The unit mentioned is sold in some instances as a "Bare Bones" RO, but not always at Home Depot.>
Very Confused <No need to be.>
Dennis
<Cheers, J -- >

Deionization Unit.. Where can they be bought?
Hello!
I am putting together a 120G reef system and have not decided on what water purification to employ. I live in a condo and have a 1/2" water pipe at the location of the tank but not a drain. I don't like the idea of the waste water produced by RO/DI units as I pay for my water usage. I have been reading your Q&A's and see references to a two column DI unit but can't locate information on units available commercially and at what cost, nor any info on flow rate, resin consumption etc. Would you have any links to suppliers, info on costs & usage?
<See our sponsors, Foster and Smith for Kati/Ani systems.>
Assuming I can locate a DI unit that isn't cost prohibitive and can produce sufficient gallons per day am I better served with this system than to locate a RO/DI remote from the tank and transport the water as needed? The nearest sink to the tank is approx 12-15' away.
<This depends on your source water and it's content. Both produce water stored in a container for later use, pumps move both easily.>
I also read recently a write-up on a Permeate Pump which significantly reduces the amount of waste water produced from the RO/Di units. Have you any experience with this unit and any guidance to share.
<RO units require optimum pressure and temperature to get the highest production from the RO membrane, this pump simply increases the water pressure to increase product vs. waste. If RO is your choice, you must factor temp/pressure/efficiency to determine likely output, which in most cases is far less than the advertised rated output.>
One more question, the waste water from the RO/DI unit, does it drain under pressure. I ask as I might consider drilling a small hole through the outside wall to drain the waste to the front garden, although this could be problematic in the winter months.
Many thanks in advance for your help.
<Yes. Low pressure, but pressure. You may want to locate it permanently at a known drain and install a drain saddle to drain into the house system. Buy the float valve set-up to avoid Marital and water disaster with either.  Test your water completely to buy the right unit.  Have fun!  Craig>

Will RO work?  Is it worth it?
Hi guys,
After two and a half months with my new 55 gallon tank I have still not purchased fish yet due to a nuisance algae, (mostly brown slime string algae on substrate and live rock ) problem I am dealing with.
To trace the source of the problem I started with the source water as that is the only thing in my tank plus the live rock.
I took my aquarium water sample (used TWP deionizer cartridge filtered) to a local water testing consultant (who really knows his water !!) who used sophisticated accurate testing and this is the results:
    Phosphates (tested for total phosphate) .22 ppm
    Silica              .80 ppm
    Nitrate     1.90 ppm
I am working towards upgrading my protein skimmer as my Bak pak 2 that hangs off the side of my sump isn't really efficient.
<About the limit of this skimmer unless adjusted optimally, w/sump more volume than 55 gal. Look into Aqua-C Urchin Pro or Remora Pro. Add to Bak Pak.>
I am extremely nervous about going the RO route, not because of the waste, as I am leaning towards the quality Kold Steril unit but of the big expense ( approx $300 for the system and then needing a plumber to install unit under my sink).
<Once you provide for the type of unit needed to remove silicates (phosphate and nitrate is a bit easier) there is very little substantive difference between RO/DI units (I suggest the DI unit downstream of the RO) besides price and service should you need it which is unlikely. Most of the component parts (filter and membrane housings, etc.) are interchangeable as are many of the after market/replacement micron and carbon block filters. RO's  don't produce as much water below 70-75 F water and <80psi (or manufacturer stated pressure) but this is simply factored into sizing the unit larger to accommodate your water needs or investing in a booster pump. You might start in the laundry room (stay away from bleach, soaps, etc) and push the drain line into the washing machine drain, hook the inlet up with a "Y" on the washer cold water valve, and route the product water into a Rubbermaid can on wheels with a shut-off valve so you don't flood the wife's laundry room. That last part is the most important. Make it easy to get to.>
Are these systems worth the cost and hassle ???  I absolutely do not mind spending the money if it will really work to rid me of this nuisance algae. I know I cannot be 100 % free of it but my tank now is really unattractive.
<Yes, they remove the source of these problems. (and tasty, ultra-pure water.>
I am also worried about the ease of operation of these units (water temp needing to be just right and flow rate just right or it won't work etc).
<See above, it will work, just not produce as much as the rated amount. You need to factor this into sizing the unit. If you need 30 gallons per day, best to get a 60gpd unit to factor in temp and pressure being less than optimal.>
    How is your experience been with these RO units and their ability to solve nuisance algae problems ????
<These are a good investment. Shop around at our sponsors!  Craig>

- RO vs. distilled water -
<Greetings, JasonC here...>
I'm sure you cringed when you saw the subject line, because I know this issue has been talked about.  However, I'm still unclear as to which option is better.  Is price the only issue, or are there other things to consider? <Well, my own limited experience with home water distillers is that their production is limited and they take a lot of electricity. You would be limited to perhaps two or three gallons per day. Now I'm sure there are more modern units that can improve on that slightly, but you sill have to boil water and cool it back down to distill it... so all in all the process is rather inefficient. An RO unit in the price range you mention would likely produce 35-60 GPD.> I can buy a used water distiller for $300 Canadian, which I believe is probably not too different than what I could get an RO unit for.  So, price being equal, which is the better option for my reef tank? <RO/DI.>
Thanks,
Steve
<Cheers, J -- >

Choosing RO/DI - Chlorine vs. Chloramine
Hello & Good Day,
Everyday reader of your Daily FAQ.  I don't really have a question per se, just wanting to pass along some information for people researching the various RO or RO/DI units for purchase.
<Okay>
Once you've decided on the Make/Model of the unit for you and your fishes and prior to placing the order, call your local Public Works and ask a simple question;
Are you using Chlorine or Chloramines for water purification?
<Almost all United States municipalities use chloramine>
Knowing the answer, and passing this information along to your vendor of choice will ensure you get the proper Carbon Filtering Media.
Case in Point - I purchased a 4-Stage RO/DI unit from Aquatic Reefs back in February. Not knowing the answer to the Chlorine/Chloramine question, not knowing there was a difference and not being told beforehand of the importance of the difference I placed my order. Unit arrived and I, excited as a kid at Christmas hooked it up and proceeded to make RO/DI unit water for my tank.
Fast-forward to Apr 16th. RO/DI water now measures 45+ TDS. I think to myself -Wow- I've only put approx 125gals through this rig and I already need to replace a filter. So I call Aquatic Reefs.
Troubleshooting the now high output and short lifespan of the filtering media led to the realization that my local Public Works is using Chloramine for purification. My original setup was shipped with Filter Media for stripping out Chlorine. The Chloramine has basically 'cooked' the Filter Media, greatly reducing its lifespan.
So, in closing, take the extra few minutes to research if you'll need the Filter Media for stripping Chlorine or for stripping Chloramine.
Then, be sure to pass the info along to the vendor.
I hope this little bit of info is able to help someone out. I'd also like to do a quick shout-out to John at Aquatic Reef Systems. Both he and the company continue to earn High Marks!
Many Thanks,
Scott
<Thank you for sending this along. Bob Fenner>

Water Pre-Treatment...
I'm trying to learn as much as possible about keeping a reef tank before I actually invest in one (or two...three...) and risk killing the fish/inverts, wasting money, and making my wife cranky.
<Ya don't want to do that! Scott F. feeling for you today!>
The biggest problem I foresee is the issue of initial tap water filtration.  The only real LFS in this area stinks (literally, on some days).  They do sell RO but walking by their tanks is a dismal experience and I don't/can't trust them to provide me with quality water when almost half of their fish are bobbing at the top of the tank, bloated, w/ eyes eaten out <shudder>.
<Lovely imagery! Scott F. with you tonight, gagging at his keyboard...!>
Determined to be as self-reliant as possible when it comes to handling my own water I set about searching for info on the Web and came across WWM.  After staring at different RO/DI units for the past week and trying to stave off the sensation of vertigo I get when considering all my options I came across the rofaqs.htm page in which you say, "This is a very good product", referring to the Kold Ster-il purifier by Poly-Bio Marine. From my (ignorant) perspective it looks great...says it can filter up to 5,000 gallon, leaves desirable minerals in the water, etc.
<It really is an excellent product>
Are there any gotcha's that I may not be aware of...? Or would this unit be all I need to turn my nasty tap water into something more suitable for sustaining marine life?
<Well, it does leave minerals in the water, which is not a bad thing...There is no waste water produced with this system. The Kold Ster-il can be enhanced to extract phosphates and silicates by utilizing and additional filter media in the second stage of the unit. Use of RO/or DI is optional, and possibly unnecessary if you use the Kold Ster-il in this fashion>
The official manufacture's website mentions using it in tandem w/ a RO filter.  Is this needed in most cases?  A big question I'd like answered is whether it produces "waste water" like RO units do (somewhat of a disqualifying factor for me...can't imagine what I'd do w/ all of it).  Could the water that comes out of it simply be added after 12hrs aeration/buffer/salt mix...or is there something else that would have to be done?
<As mentioned above- you could augment the system with an RO unit- but, in all likelihood, the Kold Ster- il will do the job quite well...just prep the water liked you mentioned above, and you will be quite happy with it.>
In the end I'm going to try to produce enough water for water changes/top off on a 80G Reef, 30G Planted FW, and 12 Mini/Nano Reef. I am guessing based on the condition of my FW tank that my phosphates are relatively high.  It would also seem, according to a cheap test kit and opaque water spots on my tank, that I have "liquid rock" on tap (Southern CA). Am I on the right path at all?...or am I completely buggered? Any info/guidance would be immensely appreciated, Jason M. Wood
<Sounds like you're on the right track to me! Good luck with your set up! Regards, Scott F>

R/O question
Hey,
I stumbled onto your site the other day after searching for discus online. let me say that you have a great site with a lot of helpful info. Let me give you a quick run down of my situation. I bought a 46 bowfront tank second hand and it came with 10 small brown and one larger blue/green discus. After a 2 hour drive and the setup 2 of the smalls died (3 months ago) so I am now left with 8 brown (orange is more like it) and the larger fish. Before and especially after looking at your website, I decided on a planted tank. So far I have regular plain somewhat med/small gravel in there with some swords which are starting to settle in. I just purchased a 110 watt lighting top so the plants should start doing better (also have a DIY in there). 
Here is the problem...
The tap water in my area is hard with about 8ph. The fish are doing ok in it, but obviously could be doing better in softer/lower ph water.
<You are correct>
One of the options I currently have is an R/O system. It would be used for drinking water as well as the tank.
<Good>
Since I have never had an R/O system before, this is where the confusion begins. 
<I am a BIG fan of these units...>
I have looked through different stores as well as different sites for ideas but have yet to find a system I am happy with (since I don't really know what to look for) and the articles on krib are from 92 and around that time. I found a system on Costco. COM which doesn't waste any water (at least it's their claim) which leads me to believe that all the others do. this system would run about 310.00 and it's their only system. Costco's RO Unit.  On EBay I found a bunch of systems for $100-$200.  I know you are seriously busy and said to check out your faq and the rest of the site (which I did and did not find an answer to this). If you can point me in the right direction, I would most certainly appreciate it.
Thanks, David
<No worries... David, there are only slight "variations" in these units... akin to "super" or "regular" gasoline... All these units "will do"... the amount of water actually "wasted" (vented, more solute laden) is actually miniscule... folks lose more water from leaks... long showers... a concern in some places... and a possibility to build.... perhaps a pond! To vent this water to... and in turn to landscape irrigation... Do take a read through the many RO FAQs filed here: http://www.wetwebmedia.com/h2opurifiers.htm the blue, linked files at top... for more opinion, input. Bob Fenner

- RO/DI Units -
I've used your site several times for info and learned a lot. I'm looking to buy a RO/DI unit for my 155 tank but I'm a little confused as to the following;
1. Is RO unit preferred over RO/DI or the opposite? 
<Depends on the source water. I own an RO/DI unit but my current water doesn't need the DI so I run it without that cartridge. Also, RO/DI water typically needs to be reconstituted before adding salt.>
2. Any preference over the best type of unit? 
<No... all are built pretty much with the same parts.>
3. Bob has mentioned that he has used units bought from Home Depot... I'm thinking of doing the same... what are the specifications I have to look for? 
<The GPD [gallons per day] that you require; not much more.>
Nilesh
<Cheers, J -- > 

RO systems 
Are average RO systems for home well water purification (i.e., under-sink models) adequate for marine aquarium use? I'm referring to the name brand systems, like Kenmore, Whirlpool, and GE. I also hear that most home systems are not suitable for well water because they don't have the antibacterial substance in the RO membrane unit, which can cause the membrane to clog in as little as 2-3 weeks. What have you heard about this? 
<The RO's for home use are designed to work with chlorinated water. The chlorine in the water prevents bacterial buildup on the membrane. Keep in mind that a good RO system usually pushes water through a 1 to 5 micron cartridge before it enters the membrane. There are units available for unchlorinated water supplies. Check with Drs. Foster & Smith or Premium Aquatics as to availability. James (Salty Dog)>

Reverse Osmosis
Real quick one tonight. I am looking at purchasing a new RO and wanted to know your opinion on the Captive Purity Brand.
<I have no first hand knowledge, but a lot of people on the message boards seem happy with them. I use and sell the SpectraPure line.>
What you know or have heard?
<See above>
The three I am looking at are the Kent Marine Hi-S, Captive Purity, and SpectraPure.
<I have always been happy with SpectraPure.>
Thanks, Bryan
<You are welcome. -Steven Pro>

RO filters...
Hello! I was reading through some FAQ's about RO/DI filters and I'm stumped again. I saw that your response to an RO filter was that it wasted obscene amounts of water,
<Probably Anthony. He is much more sensitive about them then Bob or I.>
so if I wanted to purchase a water purifier of sorts should I go just for a DI filter instead of an RO or an RO/DI filter?
<There is no difference in waste water between a RO or a RO/DI filter. DI alone, though, do not waste any water, that is until your recharge them, but that amount is still very small in comparison.>
I have heard so much raving about these filters and it seems like a brilliant idea and much healthier for my fish so I thought I'd rig up the classic rubber-maid trash can and get started, but I wasn't sure what was the suggestible route to take.
<I use a Kati-Ani DI unit and love it, but the chemicals to recharge an rather nasty, so for most people I recommend RO units.>
Also, I have massive space constraints (I live in a dorm) and while I could fit a trash can system in my room it's not easily hidden and it would take up a fair amount of space, is there any other option?
<If your tank is small, 30 gallons or less, an Aquarium Pharmaceuticals Tapwater Purifier maybe a good option. The unit is small and cheap, but the cartridges must be replaced. This can get expensive if you need a lot of water. That is why I recommend them for relatively small tanks, only. By the way, this unit is a mixed resin DI.>
I don't mind sacrificing a bit of space or beauty for my fish, but I just thought I'd ask :-) Thanks again for all your time! Sincerely, Rachael
<You are welcome. -Steven Pro>

Salt Pellet De-Ionizer
Thank you for your prompt responses. 
<our pleasure indeed>
Yes, I know I need to do something quick. I have been trying to surf and learn. 
<excellent... your best defense is always being an educated consumer>
Yes, I hang my head in shame. 
<no need for that... we are all and always learning>
I am poisoning my fishes and my self with my salt-pellet-fed water softener. Sears Kenmore, no less. (sigh). I never knew it was bad, health-wise. Are you a doctor? 
<no... not at all, my friend. And the softer use for people is not really a problem (I exaggerate <G>)... some folks have ascribed concern and complications for the excessive consumption of these chlorides.<Actually sodium. RMF> Ultimately... it simply isn't as good of a choice (with regard for purity) as an Reverse Osmosis or Deionizer for the whole house and fishes. The chloride for the fishes, now, is another story altogether. Prolonged use of salt recharged softeners has demonstrated clear symptoms of enlargement of the olfactory pores on the heads of cichlids (resembles hole in the head disease). It can be induced in less than a year when using this water (salt recharged/chloride rich). Other fishes are surely stressed too. The first thing we need to do is assess which if any fishes in your tank need soft water. Then decide if its worth the effort or perhaps you can simply enjoy harder water fishes instead (some cichlids, most all livebearers, etc)>
Again, the Aquaclear 150 is my only filter, other than the fine and massive surface area of the gravel itself, 
<which is really little help with such a big fish load... helpful, but not enough and easily disturbed>
and all those nice long roots of the water hyacinths and milfoil or whatever it is, which doubtless also harbor those nice bacteria, and are the only reason my ammonia is 0 so far. 
<agreed and wonderful... the plants are an enormously effective filter. Your tank would literally crash within days without them.>
And of course, I have been cleaning the gravel and replacing about 2 gallons every weekend. I wasn't clear on your answer about the undergravel filter. Are you saying you prefer a "large canister filter or wet dry trickle filter" to a larger Aquaclear AND an undergravel filter? 
<the AquaClear with either the canister or the wet dry. The UG filter is too hard to install at this point and not as good of a filter>
I am not familiar with canisters or wet dry trickles, but I did see some on eBay. I will try to research and read what they are. 
<definitely look into some good reference books too please. Much is explained therein. >
What size do I want? I think I would prefer an undergravel if that would do the trick, as it sounds like a "set it and forget it" type of thing...easier? 
<an undergravel filter is in fact more maintenance than a W/D or a canister filter. Gravel siphoning is necessary and laborious>
But I want to do whatever my little finny friends need. Just guide me, oh guru of the water world. Humbly, Lisa
<you are on the right track... do keep learning and growing. For know... cultivate those plants with TLC, do regular water changes (small weekly ones are best), do not buy any more fish, please do buy some good reference books, and enjoy your hobby :) Anthony>

Reverse Osmosis Filters
Hello Crew just bothering you guys yet again.
<No bother!>
I'm thinking of purchasing an RO filter and wanted to see if you could tell me what the advantages and disadvantages are to using RO water in your tank and if you would recommend an RO system over another.
<The answer to both questions starts with testing your source water and then purchasing a unit that removes any unwanted elements and produces the volume of water you need at a given temperature and pressure. The reference to "stages" usually refers to the number of filtration modules the water may pass through. This usually starts with a half or one micron filter, a carbon block filter, a RO membrane for the type of water you have, and perhaps a deionization stage to remove silicates or elements the RO membrane can't remove.>
Looking around I ran into these different systems but I don't quite know how they differ one from the other (except that one is more expensive then the other).
Two Stage SP Reverse Osmosis
Two Stage CHP Reverse Osmosis
Three Stage Reverse Osmosis
Any help would be appreciated.  Thanks.
<The best way is to start with your water and needs, and then proceed from there. Many questions can be answered this way without marketing confusion. Check out the equipment threads at: http://wetwebfotos.com/talk/index.jsp   Also look into Kati/Ani units at our WetWebMedia.com sponsors.  Craig>

RO, Kati/Ani Unit
Good Evening Crew,
I'll try to keep it brief this evening for ya'll. I've used RO water religiously since I set my 55 gallon tank up 2 years ago (FOWLR). However, I'm tired of the 30 minute drive that it takes to get to the LFS. Thinking about getting a Kati/Ani unit but can't find enough information about the two.
<First off, go to www.WetWebMedia.com and type Kati Ani into the Google search engine. You should find plenty of information that way.>
What's the difference, and do I need both?
<You do not need a RO and a DI, but you do need both the Kati and the Ani portion of a deionizer.>
Dr.'s F&S have a Kati 2 and Ani 2. Would this do?
<Yep>
R/O wastes way to much water and I don't want to be the wanker responsible for draining the local reservoir dry. Alright, one more thing, what kinda chemicals are used to regenerate the units?
<Muriatic acid (HCl) and Lye (NaOH2)
The last thing I need in my kitchen is a Meth lab. The one in the basement is more than enough (just kiddin'!). Thank you so much for your time, knowledge, and love for the hobby/lifestyle. Rob    
<You are welcome. -Steven Pro>

Improving Tap Water
Hi guys,
<Hi there! Scott F. here this evening!>
As I've stated in my previous emails, I am slowly converting from a FO to a reef tank. Right now I cannot afford an RO/DI unit.  I was wondering if a product like Seachem's Phosguard would be enough to get me by.
<Seachem makes fine products, but I don't think you can rely on a phosphate-removing resin alone to deal with phosphate on a continuous basis. I think that the best way to eliminate phosphate from aquariums is to do frequent, small water changes (like 5% twice a week). Much phosphate is regularly deposited in the aquarium through foods, so careful feeding is another thing you can do to reduce phosphate buildup in your tank. Perhaps you can treat your makeup source water with the phosphate removing resin before you mix the salt.>
I live in New York City.  Are there any other parameters (besides phosphates/silicates) that I should be concerned with in a city water supply?
<Many, many things, such as nitrate, heavy metals, chloramines, etc. A good grade of activated carbon in an inside box filter, placed in your makeup water container can help remove some of them. Using a product like PolyFilter in your system on a regular basis can remove a lot of detrimental substances from the water, too.>
As far as chlorine goes, do the salt mixes on the market like Coralife and Instant Ocean contain dechlorinators, or should I also be using a product like Amquel?
<I am not aware of any salt mixes that contain dechlorinating substances, so I'd use one of the products you mentioned, in addition to aging, filtering, and aerating the makeup water before its use>
If/when I can afford an RO/DI unit, can you recommend an efficient, low cost unit.  Also, what product should then be used to replace what the RO/DI removes from the water?
<There are a number of good units out there on the market available to hobbyists. I'd recommend a DI unit instead of an R/O for its efficiency and lack of excessive waste water production. Do check our advertisers on the wetwebmedia.com site for the manufacturers and models that they carry>
Thanks again, Adam
<And thank you, Adam, for stopping by!>

RO Water
Hello once again guys.  David D will be thrilled to hear a new LFS has opened up 15 minutes from my house....it is INTENSE, very cool.
<Allriiiiiiiight!!!>
Also, I found out this week about Inland Aquatics in Terre Haute, IN....I live in Indianapolis.  Went out there....they say it is the world's largest reef replica....it also is super intense, you guys have to see it sometime.  Huge warehouse.  
<Oh man oh man! I would love to see it!>
So anyways, I have a new supplier.  Second, an Aqua C Remora Pro is en route to my place as I write this...question...is it worth leaving the SeaClone 150 running as well as the Remora Pro, since the Remora Pro isn't quite big enough for my 120gal?
<Does the SeaClone pull nasty stuff out of the water? If it does, leave it. At any rate, it won't hurt anything it just might not help much>
Finally, I have decided that I'm going to start RO/DI for my water changes....Indy water is awful, I hate to think what could be getting to my fishes.  
<You should see the test for the Las Vegas water supply...>
So, here's the main question:  Are they all pretty much the same, or are some units better than others?  
<Yep...not much different. They all use cartridges that do the job of filtering. Personally, I haul water from a public RO/DI station that is near our local supermarket. I do this because municipal water is expensive in Vegas and believe it or not...Over the years I've grown to enjoy the weekly water outing. If you really don't want the hassle of hauling, consider skipping RO and use a DI unit only. I read emails all the time about how much waste water is produced by the RO process. One email said the ratio of waste to water on her RO unit was 10 gallons to 1 gallon! That's too much for my taste. The DI process produces no waste water...>
CTA, Hi-S, etc, etc...?  
<Again...not much different. More stations mean more filtering but you really don't need to spend a lot of money on this item>
I really only need about 3 GPD, my water supply is free of charge, and I'm fairly sure I want to go with the Kent brand RO/DI filters.  
<Kent will be okay. By the way, the units that are sold at Home Depot and other places are more permanent than a fishy unit but other than that, they are basically the same. I would check for a no-name-brand unit at one of these warehouse stores. In your case, it might would be better to just install a permanent unit on your kitchen water faucet. Then you too could have the benefits of drinking RO/DI water!>
Hate to ask for brand endorsements, but I need to make sure I do this right.  Thanks.
<You're welcome! I wouldn't spend a lot of time worrying about brands on this item. Look for what the unit removes form the water (metals, nitrate, etc)...be sure the things that it removes are what you want to remove and then check out what the waste to water produced ratio is...pick a unit with numbers that you can live with. David Dowless>
Matt

RO filtration or Carbon Filtration ?
Hello WWM crew,
I had yet another question regarding RO/DI and Carbon filters. I've been reading on how RO filters waste a lot of water but will make your water 99% pure. On the other hand, I heard that carbon filters will not waste water and will make your water 90% pure. Is this true?
<RO units do waste water and probably make 99% pure water. I do not know how much a simple carbon filter could extract, but find it hard to believe it would approach 90%.>
Would it be wise for me to invest in a dual stage carbon filter or would it still leave a lot of impurities and be a waste of money?
<If you want pure water and no waste, you should consider a DI unit. We have written much on them on www.WetWebMedia.com. Use the search terms Kati Ani or Deionization and I am sure you will find plenty.>
Thanks
<You are welcome. -Steven Pro>

Confusion over RO vs. RO/DI vs. DI
Hi, I hope you can help me out with some of the confusion I'm having over RO/DI. That phrase (RO/DI) is my problem. When reference is made to using them in a marine aquarium, are you referring to one OR the other or one AND the other together?
<A RO/DI unit has both a RO membrane and a DI canister.>
What I see for sale is mostly labeled RO units.
<They are the most popular, RO only. RO/DI are for truly awful source water and/or to make very pure product water.>
I am looking to remove primarily phosphates from my tap water. Which is more effective for this, RO or DI?
<Either will be fine.>
Will one remove some phosphates and the other make up the difference?
<Ro/DI units are very good for removing silicates.>
If the RO unit is the better choice, are the TFC units worth the price difference over the CTAs?
<Yes, you want a real RO unit, not the "bare bones" types.>
I'm anxious to get rid of the daily scraping of my aquarium glass!
<This may be part of the solution, but not all of it. Do review your other sources of nutrients and your nutrient export processes.>
There was an answer on the forum to a reader concerned about lowering phosphates that said "I recommend a DI unit instead of an RO for its efficiency and lack of excessive waste water production". Was there an ecological consideration or a reference to it doing a better job with phosphates?
<Likely Anthony and an ecological reference.>
Thanks in advance for any help you can provide.
<You are welcome. -Steven Pro>

Reverse Osmosis Systems
Hello,
<Hi Helene>
My husband is looking into a reverse osmosis system for his 90 gal marine aquarium (has fish and live rock).  Can you recommend a specific one that is reputable and where to purchase (either online or store).  We live in Maryland.
<Am sure there are some specific brands that the other folks here might well specifically recommend. I am of the opinion that most all units available are within a few percentage points similar (like brands of gasoline) and consistent with this perspective just buy/use "home improvement warehouse" models... that incorporate an in-line pre-filter... and either just the "little pressurized storage" unit included or have the device dump the finished water into a dedicated trash-can... and pump it from there. Some aquarists prefer the Deionized or combo. R.O./D.I. product... and if you're going to be using the R.O. much, there is the "waste" water volume to consider using for other purposes. Please see here re more input re these matters: http://www.wetwebmedia.com/rofaqs.htm
and the linked FAQs files beyond. Bob Fenner>
Thanks very much, Helene

RO/DI question 12/1/04
Hello All: I found a manufacturer of RO/DI units in your FAQ's and now I cannot.  Can you possibly give me a list of several recommended models/manufacturers to jog the ol' gray matter?  Thanks for the help. Scott
<Other than being sure that you get a TFC (Thin Film Composite) membrane, I would suggest shopping price.  Most membranes are made by the same few manufacturers and are of good quality.  Most aquarium brands come at a premium price, but may have better rinsed carbon cartridges (rinsing removes the phosphate introduced in the manufacturing process).  I have found many good deals on EBay as well as small independent companies that cater to aquarium folks.  A Google search should keep you busy shopping for hours.  Best Regards.  AdamC.>

SpectraPure DI unit model suggestion 11/29/04
I have been considering purchasing a DI unit to produce high quality water for