High pH Levels

[gmenke]

I have a relatively young 350g reef tank (about 3 months old)with 400 pounds of figi live rock and 50 pounds of bracnh tonga, attached is a 75g refugium/sump combination and a 30 gallon phytoplankton tank(for future use). I have a small bio load at the moment with 13 fish, 4 emerald crabs, 100 hermit crabs, about 6 turbos, 10 trochus, 6 pepermint shrimp, 4 cleaner shrimp, 1 fire shrimp and 2 green lettuce sea slug. In addition, I have 3 leather corals, 3 zenia's, 1 frog spawn coral and a octocoral. All measurable parameters are in order, I did have a high phosphate level but it is currently about 0.5mg/l. I do have quite a bit of hair algae and to combat I keep the hardness dKh at 12 and the calcium around 400. This with more snails will eventually take care of the algae. The problem I have is that the pH consistently is around 8.5 - 8.6 and I am not sure what is driving it?

Any help would be appreciated.

Greg

[briscott]

Try lowering your alkalinity and are you running a Calcium Reactor? If so watch your c02 count.

[SHB]

it could be that your c02 concentration is to low. As a product of respiration, c02 reacts with carbonates which then produces bicarbonate. This bicarbonate will buffer you PH to around 8.2(with good alk).

Another reason could be that that you have to much circulation. If circ. is too high, then to much c02 is released out of the tank.

[Randy Holmes-Farley]

First, I'd double check the ph measurement. How did you measure it? In the absence of limewater (kalkwasser), high pH is most often a measurement error.

This article also has more:

High pH: Causes and Cures
http://reefkeeping.com/issues/2005-03/rhf/index.htm

[gmenke]

Thank you all for your comments and suggestions. I have also tried to answer some of your questions.
briscott: I am running a calcium reactor, bubble count about 1 -2 per second,outflow is 1 -2 drips per second. I am purposefully running alkalinity at 12 to help combat some hair algae.
SHB: I do have fairly high circulation, pushing arond 5,000 gallons per hour with a good gyre (circular flow in a clockwise direction). I'll watch this.
Randy-Holmes-Farley: I tested using a Milwalkee SMS122 pH meter, recently calibrated as well as independent test with a 7.0 to 8.6 test kit - both gave me the same result. I read your article you suggested as well as your current months article. I do add Kalkwasser daily - 1 tablespoon using a drip system. I will continue to monitor and see what if I notice any negative impact on tank population.

[Randy Holmes-Farley]

Backing off on the limewater or providing more aeration will both bring down the pH, as can soda water or vinegar additions (both daily). :)