Hi Randy,
Thanks for offering to help. Iââ"šÂ¬Ã¢"žÂ¢ve been enjoying this forum immensely Itââ"šÂ¬Ã¢"žÂ¢s great that you and others the time to offer your expertise. In this hobby, thatââ"šÂ¬Ã¢"žÂ¢s invaluable for a marine novice like me.
I didn't want to add what is probably a repetitive post since there seems to be a lot of coverage of this., but since I've read the articles you site but have not been able to solve the problem... and since it's driving me crazy... here goes:
Iââ"šÂ¬Ã¢"žÂ¢ve got a 12g nano with 7 gal water volume, 96w power compact lights (2x24w 420 actinic and 2x24w 50/50). Lots of live rock and about 2 inches of live sand. Iââ"šÂ¬Ã¢"žÂ¢ve been using Instant Ocean Reef Crystals + RO water. When first mixed it tests at pH = 8.1, alk = 3.66 meq/l, Ca = 380. I then add 6.75 mls each of Seachem Reef Complete and Kent Pro dKH buffer (separated by a few hrs) to bring pH to 8.3, alk to 4.46 and Ca to 400. The SG is 1.025 to 1.026. The tank is kept at 80 oF.
pH is measured with a Milwaukee pH meter, alk and Ca with Sealert test kits, and SG with a hand held refractometer.
The tank is stocked with six scarlet hermit crabs, a few pumping xenia, a toadstool leather, a fire coral (Montipora), a very pretty gorgonian, some sun corals, lots of yellow polpys and GFPs. Iââ"šÂ¬Ã¢"žÂ¢d say the tank is about half way stocked at this point. Some of the corals do get fed, but the pH problem predates that. All livestock seem quite healthy and happy.
The tank was started on November 16, 2005 so itââ"šÂ¬Ã¢"žÂ¢s still pretty young. It had a serious algae problem at first but time, the hermits and addition of macroalgae to the lighted sump area has completely eliminated the problem. Nitrate/nitrite and phosphate tests always come out at undetectable (although I havenââ"šÂ¬Ã¢"žÂ¢t done those tests for 2 weeks now).
On a daily basis I check the pH in the morning to find it at 7.9. I then add 40 ml of saturated limewater (Seachem) mixed in about 300 ml RO water. Itââ"šÂ¬Ã¢"žÂ¢s added in about 20 ml increments over a period of a few minutes. That usually brings the pH to 8.1. Sometimes it has almost no effect and I have to add another 40 ml. That goes on every day during the week. Then on Sunday I do the water change (usually 3 gal). It seems to have no effect at all on the dynamics.
Prior to using limewater to increase pH I tried increasing alkalinity by adding SeaChem Reef Buffer. That was a bad idea. It did raise the pH and alkalinity, but it dropped the calcium to about 320 ppm. Iââ"šÂ¬Ã¢"žÂ¢m still recovering the system from that by using limewater additions to slowly raise the Ca again. Iââ"šÂ¬Ã¢"žÂ¢ve heard that adding CaCl2 isnââ"šÂ¬Ã¢"žÂ¢t a good idea since it adversely affects alkalinity. It seems counterintuitive to me given how much Cl- is already in sea water. Is that true?
I also tried to decrease CO2 build up by leaving the hood up and the fan on overnight. Also, I added an airstone to the sump. The tank itself has good water circulation, with the outflow from the sump pointed towards the surface and with another pump in the lower corner pushing lots of water through the back and around the rock. It generates good movement but the live rock break up strong flow in any one direction. All of that had absolutely no effect at all.
Just for the fun of it I purchased so natural sea water (Catalina) and tested it. Alk was 4.11 meq/l, pH was 8.1 and Ca was 320 ppm. So it seems to have less favorable parameters than the instant ocean mix that Iââ"šÂ¬Ã¢"žÂ¢ve been using. Nevertheless, I added some ionic calcium (SeaChem Reef Complete, I suppose CaCl2?) in an effort to up the Ca. Iââ"šÂ¬Ã¢"žÂ¢m doing that slowly and donââ"šÂ¬Ã¢"žÂ¢t know if it will work without crashing the alkalinity. If it does, Iââ"šÂ¬Ã¢"žÂ¢ll use that for todayââ"šÂ¬Ã¢"žÂ¢s water change. The idea is that perhaps itââ"šÂ¬Ã¢"žÂ¢s not just water chemistry but some sort of nutrient or other minor constituent thatââ"šÂ¬Ã¢"žÂ¢s out of whack with the artificial seawater.
My guess is that itââ"šÂ¬Ã¢"žÂ¢s just a matter of having such a small volume with lots of living things in the tank. I have no problems topping off with limewater every morning. But Iââ"šÂ¬Ã¢"žÂ¢m worried that adding all of that calcium will force the alkalinity down. Can I use NaOH instead? I work in a lab so have access to fun stuff like that. I wouldnââ"šÂ¬Ã¢"žÂ¢t want to experiment with doses on the nano so if you have recommendations on how much to use that would be great.
Whewââ"šÂ¬Ã‚¦ that was long. But I think you now have all of the relevant information. Even if thereââ"šÂ¬Ã¢"žÂ¢s not much more that I can do, it would be good to know. Part of the reason for starting the nano is to learn. Some day Iââ"šÂ¬Ã¢"žÂ¢d like to do a much bigger reef tank and also a FOLR tank, but given how expensive they are it seems that I should at least be able to keep stable water conditions in a 12 gal tank first!
Thank you again in advance. I really do appreciate your help. Your input is eagerly awaited!
Best,
Tony
