[reeferaddict]

Chin,

How big a tank are we talking here? Your effluent and bubble rates sound really high... try dropping BOTH the C02 and effluent rate DOWN by a factor of ten... then test the effluent for Alk & Calcium ... then what you need to do is calculate how much effluent at say 800pm Ca and 20 DKH Alk it's going to take to keep up with demand. To establish demand is simple, test for Ca and Alk 24 hours apart with absolutely no supplementation during the 24 hour period... Another solution to high C02 thus low PH may also be to run the effluent into a brightly lit refugium with some macro .... your algae would grow like wildfire and consume C02 AND nutrients all at the same time... run the refuge on a reverse light cycle and that will help too... I have Caulerpa in my fuge that's doing fine under PC's right now... but I'm going to upgrade to a 250W MH just to get more photosynthesis happening thus a further reduction in C02 ... I'll let you know how that works out... curious to know how your nuisance algae growth is when your reactor is running... Steve's right about the low PH being OK... lots of people keep their animals in that range... the real factor is the presence of Alk... BUT... from most of the reading I have done, I also understand that calcification as well as carbonate uptake happen much more efficiently at a higher PH, so while a low PH can be OK... better growth rates have been observed at PH's above 8. BTW... natural sea water has a PH of 8.2... period... any place you can collect a couple miles off shore where pollutants aren't a factor, you're going to get 8.2... the exception would be in those highly photosynthetic regions where it might push to 8.3... What is your corraline growth like? If it's slow then you probably have phosphates present, (which virtually ALL reactor media leeches into the water column), which probably won't register on any test kit, as they will bind quickly in the system, being undetectable, BUT there. I have actually gone back to a variety of supplements, as I find them easier to be precise with, and when I get a phosban reactor and get the phosphates out by removing any algae in the tank, I will be dripping kalk at night, and the reactor during the day, but I'm going to regulate my C02 into the reactor with a PH controller. That coupled with my reverse photosysnthesis will hopefull keep my PH at a constant 8.3... right now I have a high of 8.35 and a low of 8.15... still too much of a swing in a 12 hour period IMO...