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FAQs on Calcium Reactors, Media

Related Articles: Calcium Reactors: The Top 10 (Plus) Frequently Asked Questions about Calcium Reactors by Jason Chodakowski
Calcium Reactors and How They Work by James Gasta
Calcium, Understanding Calcium & Alkalinity, Kalkwasser, Calcium Reactors

Related FAQs: Calcium Reactors 1Calcium Reactors 2Calcium Reactors 3Calcium Reactors 4, Calcium Reactors 5, & FAQs on Calcium Reactors: Rationale/Use, Selection, Installation, Operation, Measuring, Trouble-Shooting, By Makes/Models, & Calcium and Alkalinity,  & FAQs on: The Science of Calcium & Alkalinity, Importance, Measure, Sources, Use of AdditivesTroubleshooting/Fixing, Products,

Avoid "shell-y", shiny media... Whichever, whatever media you choose, do be aware that it has a definite "useful life time"... will not all dissolve... may need "shaking up" in your reactor... periodically added to, ultimately the insoluble parts tossed, or used as substrate....

Export suggestions. Actually: Sources of Ca reactor media
Have you ever heard of people Gavin <having> problems with using clean snail shells in a calcium reactor?
<I have not.... but am of the decided opinion (Diana Fenner distributed Knop Products including reactors and media in N. America for five years; I responded to queries re) that mined materials of more soluble Calcium and Magnesium Carbonate are far better that "shiny" shells. READ here: http://www.wetwebmedia.com/calcreactors.htm
and the linked files above. Bob Fenner>

Aragonite or calcite? Use Feigl's solution      1/28/15
Paul West
Hey Bob. I was reading WWM regarding calcium reactors. In regards to aquarists being able to distinguish calcite from aragonite: "We must trust the word and reputation of the vendor along with the experience of fellow aquarists" I found a test that will show if it's aragonite. Feigl's Solution. I've found it be very easy to make and use, and certainly something most people aren't aware of.
Carbonate Staining | Department of Earth Sciences - Main Site
Mineral stains have been devised for the rapid identification of many common minerals; Reid (1969) provides an extensive compendium. The identification of minerals, however, can now be achieved with much greater certainty using modern analytical techniques (SEM, microprobe and so on). Stains have be…
Bob Fenner
Bob Fenner
Ah yes! Will you please send this graphic and your note... even just a copy paste of this interchange, to Crew@WetWebMedia.com Paul?
Ahh, I sent it to myself!
Paul West
Paul West
Paul West
Paul West
This is a photo of a sand test I did with Feigl's solution. The first 3 samples turned black, as expected. The last sample is being sold as aragonite, but obviously didn't change colors. Thus, not aragonite. Just an example of the test.


Paul West
Paul West
Some high-CA calcite reacts vigorously with vinegar, just like aragonite, but fails the Feigl's solution test. I actually have some high CA calcite that I tested. Interesting to see the "standard" vinegar test throw a false positive.
Bob Fenner
Bob Fenner
Well; depends on the concentration of the vinegar (CH3COOH, aka Acetic acid)... Calcite is far less useful to use vs. other more-soluble carbonates. DO pls send ALL petfish matters to Crew@WetWebMedia.com
Paul West
Paul West
Will do.
<Thank you Paul. BobF>

Calcite test... for Ca reactor f'/FB
Hey Bob. I was reading WWM regarding calcium reactors. In regards to aquarists being able to distinguish calcite from aragonite: "We must trust the word and reputation of the vendor along with the experience of fellow aquarists" I found a test that will show if it's aragonite. Feigl's Solution. I've found it be very easy to make and use, and certainly something most people aren't aware of.
http://www.esc.cam.ac.uk/resources/facilities/laboratories/geochemistry-labs  /carbonate-staining  
Carbonate Staining | Department of Earth Sciences - Main Site
<Ah yes! Will you please send this graphic and your note... even just a copy
paste of this interchange, to Crew@WetWebMedia.com Paul?>

calcium reactor question; media issue     8/17/11
Hello I've got a 300 g mixed reef system (incl. sump), with growing Sps and a Korallin 1502 reactor. Korallin claims it is good for up to 400g. I can't seem to dial this thing in properly.
My tank Alk meq/l keeps decreasing from 3.2 now to 3.0.
<What are you using for media? I suggest the Knop Korallith product... DO make sure you are buying this... as there are people who package other material and affix the title to it>
Also the only way for my effluent Alk to get over 15 kH is if I increase bpm to make pH get down to 6.3.
<Too low... about the limit here should be 6.8, perhaps at lowest 6.6>
Do I want a broken stream of effluent or maybe just 3 drops/sec.
<A stream should do it>
My bubble rate is 60/min. I have the Digital Aquatics controller keeping the ph between 6.4 and 6.6 with ARM coarse media.
<I like CaribSea as a company (and WWM sponsor), but not this product in most reactors. Again... switch>
Should I decrease the co2 bubble count so that the CO2 stays on longer and never shuts off or will this eventually weaken the alkalinity of the effluent? Or do I not need to worry about the amount of CO2 getting into the reactor and only worry about keeping the ph at a certain level (@6.5).
Should I increase the bpm even more?
<No; I would not... the trouble here is the insolubility, make-up of the media>
But then it will shut on and off every 10 or 15 minutes also weakening alkalinity,.. I also dose Kalk at night with a PM kalkreactor. I've been trying to adjust the reactor now for a month. What is a good bubble rate and drip rate to go with in others' experience? Thanks.
<Cheers, Bob Fenner>

Low Alkalinity even with a CR, Calcium Reactor  11/12/10
I really am puzzled. I've read your articles on Calcium and Alkalinity and found that a CR is considered a great way to maintain proper levels of CA and KH.
<Can be... though there are "variations" on how to "do this", and anomalies... mostly re core/media and quality of CO2 et al. reductant applied>
I have a CR in my 125g tank but I don't have many SPS corals. As a result, I saw my CA rising to pretty high levels (500+) so I dialed the drip rate back considerably.
<Might I ask you to measure, report the effluent pH of your reactant discharge water?>
I concluded that I was putting more CA in my tank than was being consumed. As a result of the reduced drip rate, I now have a KH of 6. My CA is at about 460.
<These are fine measures, levels>
To raise my KH a bit, I've begun an old routine of dosing KH
<I take it you mean/t Kalkwasser. This practice, addendum is fine as well>
using a pump that comes on for 1 minute at a time 3 times during the night, i.e. 2 a.m., 4 a.m., and 6 a.m. The drip rate is very slow to avoid a spike and hopefully raise the KH to about 7 or 8 over time.
My real question is why does my CR not maintain the CA and KH as expected at proper levels?
<Mmm, see the above statement. What/which media are you using? Do you have "high" quality "acid"... CO2 likely employed? What re your Magnesium concentration?>
Is the answer as simple as I really don't need a CR?
<Perhaps... what is your desire for using such?>
I would appreciate your thoughts on this.
<Let's keep chatting this up Gene; till you're satisfied w/ your understanding. Bob Fenner>
Re: Low Alkalinity even with a CR 11/12/10
Hello Bob -- nice to hear from you! Hope you are doing well. Enjoyed seeing you in Orlando.
<Ahh, a very nice time>
The effluent readings from my CR are as follows: CA=460; KH=8 -- haven't tested the pH but will do so ASAP and report.
<These are fine values... as long as the pH is not below 6.0 I would not change much here>
The media is CaribSea A.R.M.
<Ah yes... a "natural" (with too much shell/calcite IMO) product. There are others. Do try another brand next purchase>
My CR is a dual chamber design -- and I use a PinPoint controller -- I can provide HI and LO settings if you want them.
The dosing I'm doing to raise KH is Soda Ash I get from Bulk Reef Supply --
<A worthy company in my estimation>
I tested the change in pH today when the pump is on for 1 minute. It changed the pH by .05, i.e. from 8.10 to 8.15. This is occurring 3 times during the night.
<Is fine... again, I would not change this, these settings>
I use 2 different test kits: API and Salifert -- the readings are fairly similar, with Salifert more precise.
<Ah yes>
Really appreciate your help. I invested some serious money in this CR -- hoping that it would make life easier -- and for most I think it does.
<It does, and will do more if/when you are more "into" biomineralizing life>
Just can figure out why my CA rises to such high levels using it.
<Simply put there is more soluble calcium in the A.R.M. CaribSea product than ready carbonate, bicarbonate... Again, you can/could make this up in a few ways... as you are currently doing, simply adding some "baking soda"...>
That's why I backed off on the effluent drip rate -- CA was going off the chart. Now, of course, CA is more reasonable with KH in decline. With your help -- we might get this puppy dialed in properly.
<And you, BobF>

Knop C Calcium Reactor, Mg source  -- 08/23/09
Hello there.
I was wondering if there is anything I can add to my reactor aside from the arm media to supplement the magnesium in my system? Seems I read somewhere that I can add something along with the standard reactor media that will dissolve and replenish the magnesium in my tank.
<Mmm, yes... Many folks use a "clean" source of Epsom Salt, Magnesium Sulfate... and there are other Mg compounds that can be of service>
One more question I have is about Halimeda. I have this stuff growing like crazy when I run my Calcium reactor. I know that it is a calcareous algae but is there something else to check for to keep this stuff under control?
<Yes... see WWM re>
I was under the impression that this stuff does not use phosphates or nitrates for food.....which are zero in my testing for them.
Thanks again for all your time with everyone's questions. I have been reading your site for years and refer many there for your excellent advice
for us in the hobby.
Jay S
Vancouver Wa
<Welcome. Bob Fenner>

Re: Calcium Reactor (Selection) -- 08/17/09
So you think the HD is actually better than the S-IV then,
<<I like the design of the Knop HD better, yes>>
ok, I'll probably go with another one of those. What do you suggest for media reference phosphate content, Korallith or ARM?
<<I've read test results where the ARM media displayed a lower Phosphate content than the Korallith media. But, Phosphate content isn't the whole story when it comes to reactor media'¦and I also can't be sure of the accuracy of these tests. I have used both and can't say I've noticed any appreciable differences between the two in how my tank reacts, and any 'Phosphate Issues' with one's tank likely stem from other sources anyway (e.g. -- foods). The decision is yours of course'¦you can peruse the forums and go with the popular choice'¦but my suggestion with reactor media is; like with salt mixes, buy a couple to three different brands and mix/use them in conjunction>>
Thanks again,
<<Always welcome'¦ EricR>>

Calcium reactor media. Aragonite/Calcium carbonate confusion   5/2/07 Hi crew, I do know that calcium carbonate is used as the media for calcium reactors. The questions is can aragonite be used in calcium reactors and is the procedure and benefits the same as using calcium carbonate? <Aragonite is calcium carbonate. It is one of the minerals with the chemical compound CaCO3. Due to its crystal lattice its solubility is a little higher than the solubility of the other common calcium carbonate mineral calcite. Therefore, aragonite is used in calcium reactors.> Thanks, Mohamed. <Cheers, Marco.>

Calcium Reactor/Media   2/23/06 Bob, <James with you today.> what is the best calcium reactor media to used and were can I find it.  I hope you are well. <Ralph, I've always thought Knop Korallith Media was one of the best products in this regard.  Can be ordered from www.drsfostersmith.com.  James (Salty Dog)> Ralph Gibson

Makeup Water & Calcium Reactor Media using Magnum HOT 250   3/3/06 Bob & Colleagues, Ditto on the kudos to the great web site and fantastic reference books. <Ditto welcome> I have an eight month old 120 gal reef aquarium with a 20 gal refugium. I have been using SeaChem products <Good products, company, folks> to maintain proper calcium and carbonate alkalinity levels. My system loses approximately one gallon of water to evaporation per day. I use RO/DI water for this makeup water. After aeration, the RO/DI water has a pH of 7.0. <Yep> Eventually I plan on adding a calcium reactor to my system. However, in the interim, I am considering an experiment. I plan on using a seven gallon bucket for makeup water preparation. I plan on running (24/7) a Marineland Magnum 250 H.O.T. filter filled with CaribSea A.R.M. Aragonite Reactor Media for the makeup water preparation. On a daily basis I would transfer one gallon to my system and replace it with one gallon of raw RO/DI water. I hope that this will reduce the SeaChem supplements that I need to use without any significant risk to the chemistry of my system. <Should> Since I already own the Magnum filter, there will be virtually no expense in this experiment. Would you please share any thoughts that you might have on my planned experiment with me? Could there be a negative impact? Thank you for your time, J.B. White Austin, TX <I think this is an excellent idea... worth the time/trial. I would further encourage you to try other media with testing. Bob Fenner>

Toxic tank, Contaminated Calcium Reactor Media    2/12/07   I have had toxic tank syndrome for 8 months now.  My pulsing Xenia starts to turn black in less than 24 hours.  All SPS corals had to be removed from my 180 gallon 5 year old tank.  Lost some fish, scooter blenny, mandarin, Rainford goby. <Yikes... so, what have you done re the toxicity?>     To make a long story short, I changed water like crazy, searched everything for a metal contamination.  Could find nothing, so I emptied the system completely.  Cleaned it all out, replaced the sand bed, all rock, everything out, and refilled with natural sea water.  After a week, I put a piece of pulsing Xenia in last night, and this morning the polyps were starting to turn black.     I got mad, again, and the only thing I had not done was to empty my calcium reactor.  I put the media in a bowl and searched it.  Using a magnet, I found small flakes of metal of some sort, laced through the media!!!!!!!!! <Yikes...>   I have not idea how it got there!  Not from me!  I won't mention a brand name here. <I wish you would... My wife, Diana, used to distribute Knop Products in N. America... their Korallith was/is very pure...>     I will do a 100% water change as soon as possible.  I can not afford to change the rock and sand bed again!  What further steps should I take?  Carbon?  Poly filters? <Yes to both of these... this should do it> Will my new rock and sand be ok? <Very likely yes> There are no fish or corals in the tank st this time.  All have been moved to other systems.   Help   Richard <Thank you for relating your experiences... Will save many others huge headaches and grief. Bob Fenner>

- Ca & Alk, Calcium Reactor - Hello again and thanks for all the past help. My system has been running at pH 8.2, Ca 320ppm and Alk 10-11dKH since installing calcium reactor three months ago. I have tried to increase Ca by increasing bubble count to 120/min (started at 60) while keeping flow constant at manufacture's recommended starting point of 2-3l/hr. Effluent is close to ph 6.5 and 40 dKH. Trend seems to be that as I increase bubble count, alk increases but not Ca. I understand that Ca is necessarily lower when alk is high. Is this just a function of reactor media (ARM) and will I have to supplement Ca or will I eventually be able to dial in Ca to 350-400ppm with the right combination of CO2 and flow. <Well, two things come to mind - first, the ARM media is notoriously impure, which means you really can't rely on it for consistent results. Second, calcium reactors are 'really' alkalinity reactors, and by boosting alkalinity promote better availability of calcium - of course it helps that the effluent is calcium carbonate, but really, I don't see anything wrong with those numbers. Do also use the growth of your calcium consuming organisms as a guide.> Perhaps I need different media (suggestions?), <Knop Korallith.> or is 320ppm & 11dKH just fine and I should leave it alone? <Yes to that as well.> A. yongei frag is doing well so far but want to get everything right before starting to stock in earnest. Regards, George. <Cheers, J -- >

- Which CO2 to Use - Sorry to bother you again. <No worries.> I contacted a firm on the purity of the CO2, and they say they can provide any level/grade. Medical grade is 99.9% pure but is really expensive. Is there a middle of the road or is the 99.9% the way to go?? <As pure as possible is really what is necessary - but still, you're paying for the guarantee... much of the CO2 dispensed is 99.9% pure.> Also, I am having a problem trying to regulate my bubbles and maintain same. I did have water back-up to my regulator before but have added check to prevent reoccurrence. <Seems very odd - again, am pretty sure there is a check valve built into the S-IV reactor.> Could regulator be damaged?? <Quite possibly if saltwater was what got into the regulator.> If I were to replace regulator, what would you suggest?? <No suggestion - these regulators are for the most part all created equal.> THANKS <Cheers, J -- >

- Calcium Reactor Media - Dear WWM Crew, What is the difference of fine to coarse calcium reactor media? <Just the grain size.> I purchased the course Korallith (6-10 mm).  I was a little surprised at the size of the pieces.  Should I have purchased finer media? <Yes. The large media is really for the extra-large reactors.> The online store indicated that the fine or the course would work. <I think you have super-coarse - there are three grades, you have the largest. You need the medium sized one - pieces between one and two millimeters.> Thanks for help, Brian <Cheers, J -- >

- Alternate Bottled CO2 Source for Calcium Reactor - Hi Bob, I started with your book as a guide quite some time ago. I have a 90 gal. Reef and I am going to install a Knop C reactor. My question is, Can you use a paintball 5 lbs C02 bottle are they adaptable or must you use the standard one sold by aquarium stores? <Not certain, but do think finding a regulator for the paint gun bottles - in this country - are remote at best. Have seen same at trade show in Germany - small CO2 bottles with sized chrome covers very popular in the planted tank arena, but are not as far as I know being imported by anyone yet - so same would go for the regulator. Most CO2 regulators that I've seen in the states are made to fit the larger tanks, similar to the ones at the store. You can also get the tank directly from a local gas supplier - might not be polished and pretty, but functional.> Far be it from me to like the norm... hahaha <If you can find a regulator, you can use the bottle. Not sure how long they would last.> Thanks, Fred <Cheers, J -- >

Calcium Reactor Media Hi: I recently switched to Korallith reactor media, but have found that it is hard to dissolve and my calcium reactor now can't keep up with the demand, even with a high CO2 rate. <<Which size media did you use?>> (I've got heavy calcium users.) Lately I've been adding Kalkwasser around the clock for top off and I still can't get Ca levels above 380 ppm. kH is stuck around 10.5-11.0, but I can/have supplemented with Kent ProBuffer to get it up around 12 even 13, it just won't stay there unless I keep supplementing. I'm not sure what media I was using before, because I bought the reactor used and the old media worked great. It looked like it had crushed sea shells in it, but I hear that's not a well-balanced media like aragonite. <<I've not heard that, and would certainly endorse using self-made crushed coral, shells, and the like - I mean... what are these things made out of anyway?>> From reading and looking around, I think what I'm after is CaribSea ARM because it sounds like it dissolves more easily plus has a good chemical analysis. <<Personally, I don't buy into all the recent hype about reactor media.>> What media do you recommend that dissolves the most easily? <<I use Korallith and have had no problems.>> I perform 10-15% water changes every week or two. <<I would just add that I also don't subscribe to the philosophy of keeping calcium and alkalinity levels unusually high. The numbers you list are more than adequate, and are perhaps even higher than the normal, average conditions found in the ocean. I wouldn't strive for extra high numbers as they are really just unrealistic and itching for a problem like calcium precipitation. Cheers, J -- >>
Re: Calcium Reactor Media
Thanks for your reply. <<My pleasure...>> The media size is the only one that I know of that is routinely offered for sale by the various etailers out there. Each pebble is about 3 x 3 mm. <<Interesting... Knop also makes one that is about 1mm... is the size I use.>> I like your answer; it sure makes my life easier. But correct me if I'm wrong, my understanding is that natural seawater has a Ca level 425-450 ppm, <<I don't have the source right in front of me, but from my recollection the average is closer to 350-380.>> kH of 8, and a magnesium level around 1280-1300 ppm. Yes, my kH at 10.5 is elevated, but isn't my Calcium at 380 too low for long term health? I shouldn't be concerned about this? <<I don't think so... but you'd be able to tell more by the growth or lack of it in your coralline algae, stony corals and clams. Still, adding the Kalkwasser in addition to the regular input from the calcium reactor will help you move that up a notch or two if you must. Cheers, J -- >>

Calcium reactor questions... effluent properties Hello <<Greetings, JasonC here at your service.>> I was wondering what is the best ph to run my calcium reactor with Korallith media. <<Ideally, you would want the effluent pH to be roughly 6.8, not any lower than 6.5... you should also measure the dKH of the effluent and try to tune the reactor to get that to about 15-16.>> Thanks . Bill Wann <<Cheers, J -- >>

- Calcium Reactor Questions - <Greetings, JasonC here...> Good evening crew, i have been looking through the site with regard to Knop reactors, i have a model c and i think it is a very good piece of kit and reasonably priced, my only minor problem is that i have been using the CaribSea arm media for the past 12 months or so, and i have not been very impressed at all with the performance, so i have just changed to the Korallith, the only bugbear is that i am trying like mad to get the reactor effluent down to ph6.5 as instructed and I'm having no joy at all, i am putting 18 bubbles per minute through with co2 and my effluent rate is 35 drops per minute, the best i can get down to is about 6.85-6.95 and i test with a hand held Hanna ph meter, can i put more co2 through or will this give me a co2 lock in the chamber, also do you guys think that its best to get the ph down or just align the dKH on the effluent side and let the ph fall wherever (i.e 3-4 times tank dKH). <Actually, a pH of 6.8 on the effluent side is sufficient. If you want to lower that a little more, you could just slow down the effluent drip rate... cause the water in the reactor to stay in there a little longer.> Many thanks your comments greatly appreciated as always. Paul, Manchester <Cheers, J -- >

- Calcium Reactor Questions - <Greetings, JasonC here...> Hello again oh wise ones. <Oh stop it, I'm a long way from wise ;-) > I have the 180 gallon acrylic with a 60 gallon acrylic tank that I have running under the tank with frags and a few fish.  I have had a Knop C calcium reactor running down next to the 60 gallon for the last year but lately the effluent alk is down to 19 which isn't keeping my tank effluent up above 4.  When I started using the reactor the effluent was up around 35-40 which was keeping the tank alk around 10-11. My calcium is between 345-390 with the addition of the Kalkwasser slurry on a nightly basis to keep the pH up between 8.1 and 8.35.  I use the test kit that turns from blue to green to yellow.  I'm not sure which test kit it is.  My CO2 bubble counter is set at 4-5 bubbles per 15 seconds.  The effluent drip is running at about 1-2 drops per second.  I am using Carib sea media in the reactor.  What would you recommend that I do to get the effluent up to par so as to keep my main tank alk up above the 6-7 that would be the low end that it should be? <Two things, I would can the Carib Sea reactor media - the quality is too inconsistent - and switch to the Knop Korallith which is the only media that Knop guarantees will work with their reactors. Likewise, it sounds like you are expending your media rather quickly - it's probably time to swap it out.> I have had to add Seachem Reef Builder lately to get the alk up a bit to 6-7.  Any help would be greatly appreciated.  Thanks again, Jeff <Cheers, J -- >

Reactor Media - 2/13/03 Dear Anthony, thanks for that link, I've had a look and they look like they could really do the job, and they're reasonably priced, <excellent!> I was wondering if you might be able to shed some light on my small dilemma with my reactor, I have a Knop model c (good piece of reasonably priced kit, we can pick them up over here for £100.00 without gas and gauge), <agreed... I like them very much> anyway the thing is i have always used the CaribSea arm media in the past but my L.F.S have run out and i have changed to the Korallith, <a much better move in my opinion. I'm not a big fan at all of CaribSea media> the only problem is trying to get the reactor ph to 6.5. At the moment its running at about 6.15 I've just bought myself a hand held ph meter to try and test accurately, my co2 bubble count is 14 and i have been dosing on 60 drops per minute, but at this setting my dKH is coming out at 27 degrees (German) and i know it should be around 35 degrees, i have been playing around with it (i.e. decreasing the number of drips down to 50 to see if this would raise ph, but it wont budge above 6.20), when i was using CaribSea i just used to set the reactor to dKH 35 and leave it, any ideas? <absolutely... my first (and confident) guess is that the media is too large. Knop has more than a few grain sizes. I'm guessing you need a smaller grain for your sized reactor. By chance does this seem possible? Is the Korallith coarser than the ARM you were using? Should i try and set the ph at 6.5 or go for the dKH at 35. <if the previous settings ran well, I'd like to see you continue with it> I must admit this is driving me nuts at the moment, everything in the tank is great but you know how it is we reefers are perfectionists (ha! ha!). <no worries... I suspect this will be easy to tweak> All the best Paul (P.S. went for a great Indian meal last night, chili chicken and pilaf rice, absolutely superb but my god, i had a very bad case of Gandhi's revenge this morning) <Ha! What's especially funny is that here in America we call it Montezuma's revenge. Yours is funnier for the British-Indian history, though <G>. I do hope that you had a seat belt in the lav to keep you secure during the endeavor!>

Calcium reactor  Bob: <Steven Pro this morning.> Recently I set up a large calcium reactor on my relatively small 60 gal. reef tank. After running the reactor initially (day and night), the tank "crashed" and most of the inverts such as snails, starfish, shrimp, etc., died. <Sorry to hear it. Have you identified the reason behind the crash?> The die off caused an obvious water problem with the level of organic material from the decaying animals. Subsequently, an algae, or what I thought was an algae bloom occurred. I am more apt to say that the reddish brown, small stringy (1-2 mm long) material (that has coated the live rock and corals) are dinoflagellates, although I have never had an outbreak before. I scrubbed some of the rock, and although some came off, it left the rock a rusty color. The corals in the tank survived the alleged pH crash from the reactor set-up (although this "crash" is unconfirmed since I electronically monitor the pH), <I do not understand this statement. If you monitor the pH electronically, then you should be able to confirm the pH drop which caused the tank crash.> but none of them look very good since I added the reactor and this bloom occurred. My pH normally is between 7.9 (night) and 8.1. I am working to increase it. <Work harder. A pH below 8.2 is unacceptable for corals and is a sign of poor husbandry practices.> Of course, I have shut off the reactor until I can resolve this problem. <Always best to have all of your water parameters in line before starting a reactor and then monitor very closely for the first few weeks.> 1-2 weeks after this bloom, I started the reactor again (slowly and while monitoring the tank closely). I then did a 25% water change in the tank. The next day after the water change, the bloom came back even stronger (I measured phosphates at 0 in the R/O water used). At the same time I kept the reactor running 24 hours. Could this bloom be caused (or supported) by the reactor material I am using. <Possibly by contaminants in the media and by excess CO2 in water.> I am using Carib Sea aragonite in the reactor, and not the more expensive reactor material. Could some leachates in this material cause or support this bloom? <Possibly> My protein skimmer is skimming like crazy a very dark skimmate even after the 25% water change. It is strange but somehow I feel this may be related to the aragonite used in the reactor, based on how the bloom came back even stronger after the water change, but while the reactor was still running. Could this substrate have leached toxic substances that could have killed the inverts, or is this reaching? <Sounds like reaching to me.> The phosphate levels in the tank measure 0 from the most recent test. <Test kits only measure inorganic phosphate, not organic phosphate, so there could be phosphate that is undetected by your kit.> Tim <I would turn off the reactor for now. Get everything squared away and then reattempt its use. -Steven Pro>
Calcium Reactor Follow-up II
Steven: Here is my response to what I thought were your close to patronizing comments. I would prefer an opinion from Bob, not a critique of what I may have done to cause this problem. <Bob is in Australia and is unavailable.> You seem to assume that I don't have the years of experience needed for maintaining a healthy tank. Allow me to correct you, I have kept tanks for about 25 years now. Not all saltwater of course. This was an unusual occurrence because I recently changed my philosophy about calcium additions and purchased a calcium reactor. This is likely the cause of the problem. I electronically "monitor" the pH, not control it. And guess what, I don't get up at 3 am to read the pH monitor! Because I have such admirable husbandry techniques (chuckle) I have never experienced the effects of a dramatic shift in pH on tank inhabitants. <No need to get up at 3:00 AM. Your pH is lowest first thing in the morning and highest right before the lights go out. Looking at the tank and meter before leaving for work and before going to bed would give you a good picture of what is going on.> A pH below 8.2 in a reef aquarium is not "a sign of poor husbandry" as you say. <Yes it is.> "We want to keep the pH of the reef aquarium water at about 8.1 to 8.4"-Dana Riddle, The Captive Reef "pH 8.15 to 8.4"-John Tullock, Natural Reef Aquariums "The generally accepted range for pH is 8.2-8.4 in reef aquariums."-Eric Borneman, Aquarium Corals "In reef aquariums, the ideal pH does not fall below 8.2, nor climb above 8.5"-Delbeek & Sprung, The Reef Aquarium: Volume I> All reef aquariums will have fluctuating pH readings, I don't care if you sleep under your tank and spend every waking hour doing water changes, etc., it is natural to have a range. <Yes, a range that does not drop below 8.2.> Of course the target range is above 7.9, but you are taking this out of context. <If you agree, why are you being so defensive?> The pH likely dropped because of the addition of CO2 in a relatively short period of time, which in turn caused a drastic drop (remember, pH is measured on a logarithmic scale, Steve) which adversely affected the inhabitants. <Husbandry is more than just wiping the glass and doing water changes. It incorporates many other aspects, one of which is the proper use of various devices, like your calcium reactor.> The pH drop I assume could have wiped out some inverts and this in turn released organic acids into the water, along with other bad stuff, causing the algae bloom. <Yes, quite right.> The reactor is in fact too efficient and should be used on a larger tank. <The size of the reactor does not matter much in this situation. Larger reactors only allow you to go longer before having to fill the media chamber. Your problem probably lies in an overdose of CO2, which can just as easily happen in a small reactor, maybe more so.> But, because the "crash" occurred several days after the reactor was added to the system, it is the likely cause of the problem. <Not really the cause, but the instrument.> Steve--allow me to give you some advice. Soften your approach and try to be less critical, more constructive and helpful. Provide your opinion, and don't be too dogmatic. Don't automatically assume (as noted by the tone of your responses; this has not been the first email you responded to for Bob), that the person you are speaking to knows less than you about reef systems. No one has experienced every problem ever encountered. Talk to the person, not down to them. I have spent years with this hobby and have had many successful reef systems. You are not going to teach someone with my experience about understanding the science behind this hobby. So please, learn from this advice. Problems will always be present, in every reef system. I'm sure you're a nice guy, it just doesn't always come through in the tone of your email. Tim <Tone is hard to discern in the written word. We answer 30-50 emails per day and tend to be brief in our answers. Being brief is not necessarily being dogmatic. It is the nature of the forum. -Steven Pro>
Calcium Reactor  Follow-up III
pH now at 8.29 (after dripping in 5 gal. of Kalkwasser) dKH at 12 Calcium at 450 ppm Corals look great; algae bloom subsiding, no problems, mate. <Good to hear!> Lesson learned: go slow when installing a new calcium reactor, especially in a smaller system. It's these minor set-backs that build experience. Hopefully, my future experience with calcium reactors will be positive. TD <It is not an uncommon occurrence. Jason wrote a nice, simple piece on calcium reactors, http://www.wetwebmedia.com/calcreactors.htm. The most pertinent section is as follows, "So what is my baseline? Where should I start? - I would start with the manufacturer's directions. Most that I've read come with a recommendation for a bubble rate from the CO2 and a drip rate for the effluent. I would personally divide these in half and start from there. For the first week, you should test your tank and the effluent several times a day. Once you become more familiar with the equipment, and the affects of the various adjustments that can be made, you can test a little less. I still keep on a regular test schedule to make sure everything is within normal tolerances." Good luck, Steven Pro>

DSB and reactor media Hi, Mr. Calfo, Here I am again. The following questions is bothering me a lot. <No worries, my friend...> 1. Why is it a bad idea to mix some larger coarser grade sand into a 6+ inches DSB? <Various grains of sand permit or deny diffusive action (osmosis, saturation or diffusion, etc). So a bed of coarse sand only will allow better penetration of oxygen rich water (which you do not want for efficient denitrification) by virtue of the large angular shapes of the sand media and the larger spaces between grains. It also traps more detritus but does encourage more amphipods. Fine sand, on the contrary encourages more microfauna (bacteria, tiny worms, copepods) and is better suited for the establishment of a larger colony (because of the increased surface area of the smaller grain sized) of denitrifying bacteria. When all is said and done... we don't need course sand for amphipods because they will grow anywhere else easily (live rock, sump, refugium) and the trapping of detritus can be a nightmare to keep up with and in the typically poor current displays of so many aquarists leads to the crash of a sand bed unfairly blamed on DSB methodology. You want sugar fine sand if you are gunning for denitrification and it really needs to be as deep as possible (solid 3" minimum but over 5" is much better)> 2. I just bought some calcium reactor media by Dupla. The media looks like some crushed coral and shells, and I am sure they are. I have also checked out the calcium reactor media by CaribSea, and it too looks like crushed coral, but it is claimed to be aragonite. Why??? <Not all shell/calcareous media is aragonite. About 20% of the beaches in the Caribbean are said to be composed of aragonite... the rest are calcite. Just a different form of calcium carbonate but a big difference nonetheless. I have seen some studies about reactor media... not the least of which are reports from the notable aquarist/author/manufacturer Daniel Knop. Avoid shell and crushed coral at all costs. They are least effective and most likely to impart undesirable elements. Champion Lighting and Supply have an excellent bulk calcium reactor media that is outstanding. Do look into it. Let them know I suggested it if you like.> 3. Since aragonite and crushed coral look so much alike, how can we tell one from the other by their appearances? Is aragonite crushed SPS coral? <We aquarists cannot tell visually. It is a molecular difference. The notable advantage is that it dissolves easily and at a higher pH. Calcite is tough to dissolve. We must trust the word and reputation of the vendor along with the experience of fellow aquarists. Many of my friends swear by the bulk media at Champion.> Sorry to bother you. Thank you for your time. <No bother my friend, always a pleasure.> Sincerely Samuel

Calcium Reactor Media hi bob, <Howdy> hope you're doing well. all is fine in my set-up, though started wondering abt. my calc reactor, recently -- I have an Aquamedic calc reactor (large, for up to 250 gallon tanks), still using the original media it came with. I've been using it for abt. 7 months. when do you think is the best time to replace the media? abt. 6 mo.? is Korallith a brand you'd recommend? thanks! <Mmm, I wouldn't "just" change out the media on a timely basis... that is, just for the sake of it... I trust you're testing for calcium and alkalinity. I would switch or augment the media when these become limited. Brands, products do vary quite a bit. I encourage you to check with actual end-users, like through chatforums (ours: http://wetwebfotos.com/talk/) and experiment with a few yourself to see what gets you where you want to go with the least cost, most ease. Bob Fenner, whose wife does distribute Knop Products in N. America., just a timely admission> - Javier

Media for my Calcium reactor I am getting ready to start my Calcium reactor. Please tell me what you feel, or if there have been any studies, what is the best media for my Calcium reactor. Also, I can't seen to do a search on WETWEB any more please help:) Thanks, Brad:) <Many routes to go here with the media question... not just "pure" or easy to dissolve "Aragonitic" materials... You want, need other alkaline earth compounds... I suggest a bit of experimenting with some "standard products" like CaribSea's fine offerings... Try "a bag" of various size/grades of their types and tell me (please) what calcium, strontium, magnesium, alkalinity, pH values you come up with in your particular circumstances (type of reactor, pH of effluent, time in use, amount of reactant...). Please do record your findings in a bound, permanent notebook, in ink. On the "search question", I am sending your msg. to Mike.K my cohort on functionality and looks for WWM (it's only us two...). Miguel, what say you? Bob Fenner, who maybe should private label...>
Re: Ca Reactor cont'd
I have pretty much decided to get this unit after further research.... My question now has to do with he material to put into it... CaribSea ARM Ca Reactor media says that it DOES have Phosphate and Silica... but less than others.... Is there one that claims they have none? <Not as far as I know> I looked and looked but could not find a Ca monitor... <Ah... most folks settle on a pH monitor for the effluent... calcium can be calculated, adjusted by way of this measure and flow rate> I think this would save money in the long run.... I doubt this exists... I would have found it on the net.... If it is not on the net it ain't real Heheheheh... just kidding... I did find a monitor but it was not meant for this purpose and the range is too low.... only up to 10ppm and as low as about 20 ppb. Thanks as usual.... How can we... your audience say thanks? <You just have my friend> Is there something we can do? <Help others>
Regards, Rob
<Bob Fenner>

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