Reverse cycle pH question

[Keko21]

Hey All,

I have a bit of a puzzle to figure out- I have macro algae growing in my sump and have it set to a reverse cycle to help manage pH. During the day my pH hovers kind of low between 7.8 and 8.0. Contrary to what most people see my pH jumps UP at night most recently to 8.6!! My chaeto is about the size of a basketball right now so a lot of photosynthesis at night, but should I change my sump light cycle to have it on sporadically during the day to see if I can balance this out? Thanks!

 

[Randy Holmes-Farley]

Where are you measuring the pH?

That jump is quite large, and may indicate low flow? through a sump where you are measuring pH.

 

[Keko21]

The pH probe is in the sump in the skimmer chamber before the refugium. I've got a small powerhead in the refugium to turn the chaeto, and the skimmer is blowing water where the probe is. In the display I have a Red Sea Gyre and another power head on the other side. One of the four return nozzles is above water to create a good amount of agitation.

 

[Randy Holmes-Farley]

If that pH range is accurate, the tank has relatively poor aeration and I might look to increase it.

 

[Keko21]

If that pH range is accurate, the tank has relatively poor aeration and I might look to increase it.

Any thoughts on how to do so? As I mentioned there is a lot of surface agitation from the return, and I have a CO2 scrubber on a closed loop with my skimmer. Getting a line outside unfortunately isnt an option.

What if I put my sump light on a 6 hour on 6 hour off schedule as it seems the chaeto is really doing good work at night?

 

[Randy Holmes-Farley]

Any thoughts on how to do so? As I mentioned there is a lot of surface agitation from the return, and I have a CO2 scrubber on a closed loop with my skimmer. Getting a line outside unfortunately isnt an option.

What if I put my sump light on a 6 hour on 6 hour off schedule as it seems the chaeto is really doing good work at night?

More aeration does not necessarily mean with low CO2 air. The range from the daily low to the daily high is larger than usual, which to me means less than normal aeration with any air. It's not necessarily a problem, but if it indicated low O2 was a possibility, then I'd be concerned.

An airstone in the sump, especially when it is not lit, might help the oxygenation, even if it might bring down the pH high.

 

[Keko21]

Yeah…so I’m gonna go out on a limb and say this is a probe calibration issue…