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FAQs on Tap/Source Water Use for Marine Aquariums, Testing

Related Articles: Treating Tap water for Marine Aquarium Use, Water Purification Using Reverse Osmosis,

Related FAQs: Treating Tapwater 1, Treating Tapwater 2, Treating Tapwater 3, & FAQs on New Water Treatment: Rationale/Science, Chemicals (Chlorine, Chloramines, Trihalomethanes...), Filtrants, Techniques/Tools, Troubleshooting, Products by Manufacturer/Brand, DIY Treatment Chemicals/Tools, & Reverse Osmosis Filtration, Specific GravityWater Purification Using R.O 1. RO/DI 2, RO/DI 3, NitratesWater Changes

Guess which one is freshly mixed RO/DI     2/25/15
You bet it's the ammonia rest on the right.
What the heck? Water is about 24 hours old heated with aquarium heater in clean plastic storage box.
I'll test some in a new sample container, this is odd.
<I'd test the kit itself... with some distilled, spring... water of known zero Ammonia concentration... Hey; not by any chance do you happen to be standing in a litter box are you? Bob Fenner>

Re: Guess which one is freshly mixed RO/DI      2/25/15
Update on this case
1.) Fresh tap water is clean on test kit
2.) Removed D/I cart and tested right out of the R/O membrane. Better but still contained ammonia.
<Appears that there's something... biological (live or not) "in" the line or cartridge... time to systematically disassemble, bleach, rinse the lines, toss/replace the modules, media; including the tris membrane>
I’ve been suspicious of this coral-life flo II unit ever since I bought it last year. 4 stages new AquaFX filter media ordered (not from corallife brand).
<Mmm; not a fan... Here comes da rant: Since the co. was sold... the "consolidation" (a euphemism) in the trade... the new owners not into QC, innovation... other than marketing and optimizing profits>
I also bought a TDS tester to monitor. If TDS is nearly 0 ammonia should not exist, right?
I’m buying some jugs of water to do a water change before my tank crashes.
<A good idea>
I’ve read about ammonia leaching out of RO once it has been depleted by municipal water. It’s a scary failure mode since it’s supposed to be pure.
<Again; yes; I agree. Bob Fenner>

Water testing     3/19/14
Hi everyone
I was talking to the owner of my LFS last night and the conversation came to the terrible quality of water test kits available to the hobby
<Mmm; some better than others... Hach, LaMotte... kits made for others by them>

and the huge price gap between hobby kits and what our local water district uses. We finally decided that a really serious hobbyist and certainly an LFS should send a water sample to a lab at least yearly to get pro quality analysis, so here are my two questions; First, what tests would you run that perhaps even the average store doesn't usually test for?
<A tough question... You/all should know that samples change with time... not the same w/ shipping. Maybe just the standard nutrient tests: NO3, HPO4... perhaps Potassium for summat new>
For example, what tests would you run to prove that your R/O unit was doing a tip-top job?
<Mainly TDS, conductivity.... one could use a mass spec...>

Second, if you've ever done this, is there a lab you'd recommend?
<Most any QA, quality assurance lab will/would do>

Thank you in advance
<Thanks for sharing. Bob Fenner>

RO/DI Laboratory Analysis     7/7/13
WWM Team,
I have a question about water quality that is related to some advice that Bob Fenner provided me a while back. I have been trying to solve the overgrowth of a white substance on my live rock that Bob identified as a mix " BGA, Protists and Sponges/Poriferans.." Since then I have taken his advice and focused on RedOx and better mechanical and biological filtration.
One area of focus was on the RO/DI water that I create at home. The TDS meter was showing 0 but I decided to send the product water to a lab for analysis right after breaking in new membranes. The results are in the attached PDF. My questions is... would the Silica level at .21mg/L be a reason for concern?
Should I be worried about the trace presence of Boron, Iron, Silver, Potassium in the product water?
<Mmm, no; not really>
I am tempted to run the product water through GFO before I mix it with salt it to pull out the Silica, but I wanted to get another opinion. I currently use a Coralife PureFlo II 4 stage RO/DI unit.
Thanks again for what you do!!!
<This water is fine for all pet fish uses. You could easily have "other" chemical influence/issues from dissolving substrates/rock and foods. Bob Fenner>

Boron 0.091 mg/L

Iron 0.040 mg/L

Potassium 0.450 mg/L

Silica 0.21 mg/L -- 0.05

Silver 0.0006 mg/L

Water Quality Report, source water for SW, potable uses  - 03/30/10
I have a 90 Gallon Salt water tank, and am establishing a 20 Gallon QT tank in plans to obtain some new fish in the next month or so. I have been buying RO water for my tank, and am debating on buying an RO/DI unit.
<Do it... much cheaper, more convenient in the not very long haul>
However after reading the FAQ's I saw some of you aren't opposed to using good tap water that's been aged and treated.
<Oh! This is so as well. Depends on the quality of your source water mainly>
I obtained a water quality report from the water company, and am pasting below. There is <are> some copper and nitrates present. Would you try using this water, or is it not worth the risk? Thanks, Pam
Contaminant (units) Ideal Goal MCLG Highest Allowed Level MCL Detected level Date sampled Range of detection Violation Source
Total Coliform Bacteria 0 Presence of Coliform bacteria in >1 sample / month 4 positive samples 6/08 25 samples tested Yes Naturally present in the environment
Copper (ppm) 20 samples tested, no samples were above AL 1.3 AL=1.3 0.252 6/08-9/08 0-0.464 No Corrosion of household plumbing systems; Erosion of natural deposits; Leaching from wood preservatives
Lead (ppb) 20 samples tested, 1 sample above AL 0 AL=15 9
6/08-9/08 0-38 No Corrosion of household plumbing systems; erosion of natural deposits TTHM (ppb) Trihalomethanes N/A 80 71 11/26/2007 N/A No By-products of drinking water disinfection
Haloacetic Acids (HAA5) (ppb) N/A 60 29.8 11/26/2007 N/A No By-products of drinking water disinfection
Barium (ppm) 2 2 0.016 6/28/05 N/A No Discharge of drilling wastes; Discharge from metal refineries; Erosion of natural deposits
Fluoride (ppm) 4 4 1.1 10/08/08 0.7-1.1 No Water additive which promotes strong teeth; Erosion of natural deposits; Discharge from fertilizer and aluminum factories
Sodium (ppm) N/A N/A 11.2 5/19/08 N/A No Erosion of natural deposits; Added to water during treatment process.
Nitrate [as N] (ppm) 10 10 2.4 1/08-12/08 N/A No Runoff from fertilizer use; leaching from septic tanks, sewage; Erosion of natural deposits
Chlorine (ppm) MRDLG =4.0 MRDL=4.0 RAA 2.03 2008 1.6-2.7 No Water additive used to control microbes
<Mmm, the NO3 is a bit high, but again, depending on what you intend to keep, this water is not "that bad". I take it you drink it, use it for cooking... Bob Fenner>

Water Quality... source, /potable and SW use  11/20/09
I got my well water tested by a lab for minerals, to help set up my filter system for drinking and for my reef tank.
aluminum 0.299 mg/l
antimony <0.500 ug/l
arsenic <0.500 ug/l
barium 0.039 mg/l
beryllium <0.003 mg/l
boron 0.867 mg/l
cadmium <0.100 ug/l
calcium 3.31 mg/l
chromium <0.010 mg/l
cobalt <0.020 mg/l
copper 0,010 mg/l
gold <0.040 mg/l
iron 0.394 mg/l
lanthanum <0.020 mg/l
lead 1.54 ug/l
magnesium 0.332 mg/l
manganese 0.59 mg/l
molybdenum <0.020 mg/l
nickel <0.050 mg/l
phosphorus 0.096 mg/l
potassium <0.050 mg/l
scandium <0.050 mg/l
silicon 3.48 mg/l
silver <0.010 mg/l
sodium 247.0 mg/l
strontium 0.102 mg/l
titanium <0.010 mg/l
tungsten <0.050 mg/l
vanadium <0.010 mg/l
zinc 0.018 mg/l
hardness 9.63 mg/l
ph 7.56
What elements should I target for filtering for my reef tank? I will be filtering iron, manganese and sodium to meet the guidelines for Canadian drinking water quality. RO/DI filters produce to <too> much waist <waste> water, I worry about the waist <waste> because the well is my only source of water.
<Most of the elements you list are found in seawater, although not in the same proportions. I'd consider making up an additional water purification system using the same type of canisters used on RO systems. Three canisters containing a 5 micron filter, carbon block, and a mixed resin bed, should provide you with good drinking water by using the output water from the filtering methods you state above to feed the canisters. In your reef system use a Poly Filter, this will remove most heavy metals including copper, and is also a great media for increasing water quality in fresh and marine systems. You may want to read here.
thanks Miles
<You're welcome. James (Salty Dog)>

Top off water and Testing for RO Water TDS 4/27/09
Bob and the Gang,
<Hello Joe>
Hope all is well.
My 135 G Reef tank loses a lot of water due to evaporation.
I add a fair amount of RO water to top it off weekly.
<Am I to understand you top off the tank once a week? Or do you mean you lose a lot of water over the course of a week. If you are topping off only once a week I suggest you try to do it more often, the longer you wait before topping off the tank, the larger the swings in the specific gravity of the water your tank will experience>
<There are auto top off devices available to top off the tank for you and provide a more consistent environment for your tank inhabitants. Search 'ATO' on the Google search box at the bottom of WetWebMedia.>
My question is, should I be adding something to my top off water? Never thought I had too, but I've read a
couple of places where they recommended adding something to keep the PH up.
<It is possible to buffer the water, but not necessary, assuming you are testing and adjusting alkalinity as needed. Just continue adding topping off your tank with RO water, pH swings will be less noticeable if top offs are done on a small consistent scale like with an ATO. You can also aerate your top off water to remove CO2 from it prior to use.>
Also, how can I be sure that my RO unit is working properly (I have the Coralife Pure-Flo)? Is there something I can use to test the RO water? I was reading about TDS testing but wasn't sure if that was necessary.
<I would highly recommend testing the Total Dissolved Solids from the effluent hose of your RO unit. Membranes do lose their potency over time from normal use, but this can be accelerated depending on what chemicals your city adds to the water. Testing TDS is one of the most simple ways of checking the quality of effluent coming from a RO unit, and basic TDS meters can be had at a very low cost.>
<You're welcome. Josh>
Re: Top off water and Testing for RO Water 4/27/09

Thanks Josh. Yes I'm topping off roughly every week. I usually lose close to 10 gallons a week! You make a good point about trying to do it more often to avoid larger swings in specific gravity. I'll definitely try to
do that.
I'll also look into a TDS tester.
Thanks again.
<You're welcome, I think you will come to enjoy not carrying full buckets of water around. Josh>

Hand Held TDS Meter 1/6/08 Dear WWM Crew, First let me thank you for the knowledge and unselfish time you donate to aquarist in need. I read this website every day to gain knowledge, the books help too. <Thank you Sue.> I just thought I would pass along some information. For everyone who says they can't afford or don't have a TDS meter. Go to Walgreen's Drug store and located by the Britta Water Filters you will find a hand held TDS Meter for $14.99. It is made by HM Digital and is factory calibrated and adjust for temperature. Armed with this knowledge everyone can afford to have a TDS meter. I know that this hobby is expensive and can strain the pocket book so I wanted to let everyone know about a low cost and accurate solution. Happy Reefing! Sue Marietta, GA <Thank you for sharing this information. It will be passed along! ScottV.>

What to test for from my well water? Five years ago I had a 125 gallon salt tank. But used it mainly for carnivorous fish. I have been dreaming of getting into a reef setup. I recently found a great deal. And have just purchased a 750 gallon tank. I now live with well water and want to make sure I know what I'm getting out of the ground. I do plan on getting it tested, but have a few specific questions in regards to the required tests. My questions are: 1. Which tests do you consider absolutely necessary since their seems to be and endless amount of things to test for. <I would consider Ammonia, Nitrite, Nitrate, Chlorine, Copper, pH, and Hardness to be necessary tests when determining whether or not well water is suitable for use in your reef tank to be.> 2. I would like to know what certain elements in my water would dictate either my using RO, or RO/DI, or just Kold. I really do not want to tax my well with what I understand to be a wasteful RO system. Unless absolutely necessary. <I, personally recommend that everyone uses an RO/DI system for their reef tank. Many units have lower waste water to clean water ratios. However, if you feel so inclined to use your well water, discovering traces of Ammonia, Nitrite, Nitrate, Chlorine, or Copper would serve as a red flag, and should deem the well water unsuitable. Low pH and low hardness are not make-it-or-break-it factors, but can cause many headaches down the road.> PS. Your site seems to be the most complete I have found for information.  After reading a ton of previous questions I see their are endless possibilities with how best to set up systems. <You've hit the nail on the head.> I thought I had a plan until finding this tonight. Now I know I better spend a little more time gaining some knowledge before setting it up.  Thanks for your time and expertise. <Glad I could be of assistance, Mike G>

What to test for from my well water? - II Wow, what a great/quick response. Thank you. <You're welcome.> Would it be sufficient to just use my RO when preparing to do a water change? Or is it recommended that you also leave it running 24 hours a day to aid in filtering the tank? Can you recommend any manufactures? <What do you mean by "filtering the tank?" An RO/DI unit takes tap water, or, in your case, well water, and converts it into a much more reef-appropriate water. You use it to prepare water for water changes and for top-off, but hooking it up to a reef as a filter, which I assume you want to do, would convert the saltwater to freshwater, and waste much of the water. Before you knew it, your 750 gallon tank would be half full of near fresh water.> I was told to buy Aqua Medic products. <Which products to buy is completely your choice.> I'm considering buying: 1. Aqua Medic Turbo Floater 5000 @ 975 GPH skimmer. 2. Osmotic 4 stage R/O 300 GPD 3. Riff 2000 Wet/Dry Any feeling on these in particular? <1 and 2 look good to me, but I would never personally recommend a wet/dry unit on a reef tank. It serves only as a nitrate factory.> Thanks again, I will hold on the questions until I further educate! <No need. This is a place to get answers and to help you. We don't mind answering your questions at all, Mike G>

Water testing This question is more for Steve and Anthony (sorry Bob) being from Pittsburgh do you know where I can take my tap water to get it tested? I live near Cranberry and would like to know if my tap water is ok to use straight for filling my tank or not.  <actually... your water authority publishes an annual report and weekly (perhaps daily) ones are available as well. Usually available just for their asking... do give them a call. They must lawfully disclose such information I believe. Do consider that all tap water changes seasonally though... as such, for a truly tweaked tank... you may still want to consider purified/buffered water to employ a consistent quality of water for tank use>> Thanks You all are great and Bob your book is like a bible to me and doesn't go far from me. Lunch breaks and everything else are spent reading and rereading trying to soak it all in. but still here I am on the site trying to learn more. Colleen Thanks in advance Pittsburgh, PA <best regards and thank you! Anthony>

What's On Tap? (Source Water Testing) Hi guys, <Scott F. your guy today!> In an effort to get to the source of my nuisance algae problem (brown slime on live rock and substrate) which seems to be either brown diatom algae or Cyanobacteria. I am getting my tapwater and tank water professionally tested. My hobby grade test kits (Hagen and Red Sea) all say my phosphate, silicate and nitrate levels are really low yet my tank says otherwise! <Yep- you'd be surprised what happens in an aquarium. It is entirely possible for a test kit to read undetectable levels of these undesirable substances, yet still have a tank full of algae-covered rock and sand. Many of the compounds that fuel nuisance algae growth get bound up in substrates and rocks, and provide a continuous nutrient source.> I am taking two samples ( in sterile containers sent to me by the water consultant) , my tap water alone and my tank water. I am asking him to test for Phosphate (should it be for organic, inorganic or total phosphate ??) <Well- could be all of the above...I'd look into organic phosphate, myself> , silicates and nitrates. While I am doing this baseline testing is there anything else I should test for which is important for my FOWLR tank. <Well, I think that you're covering most of the major nutrients for nuisance algae outbreaks that are found in source water> His pricing is very reasonable and I need to know the source of my Cyano slime so I can act accordingly. THX. <Well, source water is an important source of these substances, but don't rule out some of the more basic things, such as your husbandry practices (i.e.; water changes), protein skimming, feeding habits, etc....All are potential contributors to nuisance algae blooms...Look beyond the obvious, but don't forget to look at the "basics" yet again. I'm sure that you'll get to the bottom of your problem! Good luck! Regards, Scott F>   

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