The other reason your Ph is low

markwayts · Jan 15, 2022

Ok so I have an observation with myreef tank. I have been clearing space recently because my tank is overgrown. A large part of my success/problem can be contributed to the extra growth i got once i started dosing kalkwasser. Raising my ph from a high of 8.1 to a high of 8.35 made my growth explode. So i work on my tank at night after work and the tank lights are off. I left the lights on for an extra hour or so a couple days in a row and my Ph jumped way up at night and to new highs during the day. Does this mean my tank is starving for light?

AJsReef · Jan 15, 2022

No you aren’t necessarily starved for light. Increasing photo period will increase photosynthesis which in turn will reduce CO2 and increase pH. You’re just allowing your corals to “do what they do” longer.

You could extend your photoperiod if you’re inclined to do so. You may see diminishing returns with coral growth if you extend it too long.

Miami Reef · Jan 15, 2022

Refugium does the same thing.

markwayts · Jan 20, 2022

Yea i agree with both of you but i know my light is weak and my tank is overstuffed with liverock and coral. I hold my Ph up by dosing kalk 24/7. I really feel like since i can't add more intensity maybe duration might be almost as good.

Randy Holmes-Farley · Jan 20, 2022

markwayts said:
Yea i agree with both of you but i know my light is weak and my tank is overstuffed with liverock and coral. I hold my Ph up by dosing kalk 24/7. I really feel like since i can't add more intensity maybe duration might be almost as good.

pH is definitely not a suitable way to decide if the lighting intensity is appropriate.

pH certainly rises during photosynthesis due to CO2 consumption. The opposite happens at night, when respiration dominates, adding CO2. But many factors impact the pH effects, and perfect aeration would prevent any rise with any amount of light.

markwayts · Jan 21, 2022

Huh. Perfect aeration. Hadn't thought of that. So what you are really saying is that my Ph daily fluctuations are more about bio load than light and that makes sense. My thought on the lighting is if i extend my daylight by a couple hours it will drive my afternoon high Ph up and a shorter night will give my corals less time to bring it back down thru respiration.

Randy Holmes-Farley · Jan 23, 2022

markwayts said:
Huh. Perfect aeration. Hadn't thought of that. So what you are really saying is that my Ph daily fluctuations are more about bio load than light and that makes sense. My thought on the lighting is if i extend my daylight by a couple hours it will drive my afternoon high Ph up and a shorter night will give my corals less time to bring it back down thru respiration.

It's about both, but if that lighting change increases photosynthesis, it will help raise pH.