Bringing pH DOWN?

[togitnj]

My pH is about 8.5, my alk is about 250 ppm, and my Ca is about 500. I'm having some very very minor precip (just on the suction cups that hold my heater and filter return). The rest of my numbers are good, and my fish and corals all seem happy, but how do I bring my pH down safely?

 

[ivanfj]

I could be wrong on this, but as far as I know, carbon dioxide (CO2) brings down the pH level. Maybe try running some carbon. (Carbon + oxygen in the tank = CO2)????? Just an idea.

 

[ophiura]

Are you dosing anything for calcium/alkalinity at the moment?

 

[togitnj]

No. The Alk is fine, and while the Ca is high, I've been adding a cleaner crew and some corals that will start to consume a lot of the Ca in the water. That ought to bring the buffering capacity down a little, which I think will be a good thing, because right now it's so high that I can't even induce a pH drop.

 

[acekjd83]

activated carbon will not spontaneously form carbon dioxide (it is a highly endothermic process), and carbonic acid will not stay dissolved in solution if there is any sort of surface agitation (like protein skimming) or strong currents. The added livestock may help with the pH, however, by consuming some of the buffer and slowly releasing organic acids... I would wait and see how the chemistry balances for a couple weeks before trying artificial additives.

 

[togitnj]

Thanks for the suggestion. I went to the local shop and they recommended Wardley's Sodium Biphosphate, but in extremely small doses (half the manufacturer's recommended) with both time and testing inbetween a second dose.
Since the livestock don't seem the least bit stressed, I agree with the waiting philosophy, but I did try a 10% water change with a new mix and the half dose of the Wardley's stuff and it seems to have worked - both my hardness and my pH went down a little, which was all I needed. I'm not sure it'll stay that way, but I can't imagine why not, since the only identifiable source of this problem was the salt mix.