I’d like to stabilize both pH and alkalinity because they are generally stable on the reefs, and swings of either have been shown to be bad for coral.
I dose carbonate (aka soda ash, from Core7) for alkalinity and Ca, which increases pH a moderate amount. It’s fairly easy to dial in the alkalinity to be relatively stable around my target of 8.5 dKH with this method. In order to stabilize it, I’m dosing a lot less when the lights are off because there is less consumption and it would rise too much if I dosed the same.
Problem is, there is a natural cycle of pH in our tanks where it rises when the lights are on from photosynthesis using CO2, but otherwise is always drifting down from metabolism of everything that’s alive in the tank producing CO2. So there’s a daily cycle of pH increasing during the lights-on time and decreasing during the lights-off time. My typical pH cycle is about 8.0-8.3. 8.3 is the natural pH of reefs and what I consider my pH target. A little higher would be ok, but not the really high pHs that some people like since ocean animals aren’t evolved for that, they need some H+. The lows are made worse by the decreased dosing of carbonate at night, partially offset by lighting the refugium at night (photosynthesis).
Calcium hydroxide (kalkwasser aka limewater) has a lot stronger effect of increasing pH than does carbonate for the same amount of alkalinity added. But saturated kalk is a lot less concentrated than saturated carbonate, so you’re dosing a large volume, limited by evaporation in high-consumption tanks. Putting aside the vinegar thing since I’m not going to do that.
My thought is to dose calcium hydroxide when the lights are off, enough to stabilize the pH closer to 8.3 without raising the alkalinity much higher than target, about 8.5. And without being too much volume relative to evaporation. Then dose carbonate (and the other parts of Core7) when lights are on to stabilize the alkalinity. I’m not sure how it will work out exactly but my intuition is that it’ll probably be something like 1/3 alk from hydroxide and 2/3 from carbonate given that consumption is less at night. As an added bonus it would be cheaper and probably easier once dialed in.
I’ve seen the Meckley approach of just dosing calcium hydroxide to keep pH stable and not worrying as much about alkalinity stability, but I think it should be possible to dial it in to make both relatively stable. At least more than they are normally.
To me it seems this is a pretty obvious approach so I‘m assuming others have already tried it. Anyone have any experience?
I dose carbonate (aka soda ash, from Core7) for alkalinity and Ca, which increases pH a moderate amount. It’s fairly easy to dial in the alkalinity to be relatively stable around my target of 8.5 dKH with this method. In order to stabilize it, I’m dosing a lot less when the lights are off because there is less consumption and it would rise too much if I dosed the same.
Problem is, there is a natural cycle of pH in our tanks where it rises when the lights are on from photosynthesis using CO2, but otherwise is always drifting down from metabolism of everything that’s alive in the tank producing CO2. So there’s a daily cycle of pH increasing during the lights-on time and decreasing during the lights-off time. My typical pH cycle is about 8.0-8.3. 8.3 is the natural pH of reefs and what I consider my pH target. A little higher would be ok, but not the really high pHs that some people like since ocean animals aren’t evolved for that, they need some H+. The lows are made worse by the decreased dosing of carbonate at night, partially offset by lighting the refugium at night (photosynthesis).
Calcium hydroxide (kalkwasser aka limewater) has a lot stronger effect of increasing pH than does carbonate for the same amount of alkalinity added. But saturated kalk is a lot less concentrated than saturated carbonate, so you’re dosing a large volume, limited by evaporation in high-consumption tanks. Putting aside the vinegar thing since I’m not going to do that.
My thought is to dose calcium hydroxide when the lights are off, enough to stabilize the pH closer to 8.3 without raising the alkalinity much higher than target, about 8.5. And without being too much volume relative to evaporation. Then dose carbonate (and the other parts of Core7) when lights are on to stabilize the alkalinity. I’m not sure how it will work out exactly but my intuition is that it’ll probably be something like 1/3 alk from hydroxide and 2/3 from carbonate given that consumption is less at night. As an added bonus it would be cheaper and probably easier once dialed in.
I’ve seen the Meckley approach of just dosing calcium hydroxide to keep pH stable and not worrying as much about alkalinity stability, but I think it should be possible to dial it in to make both relatively stable. At least more than they are normally.
To me it seems this is a pretty obvious approach so I‘m assuming others have already tried it. Anyone have any experience?
