Keeping PH stable or what is an acceptable swing without causing trouble?

[JohnBa]

So I’ve been reefing maybe 2-3 years with me being in the military I have tear down my tank every other year maybe, so I recently I downgraded from a 240g to a 120g tank. Ever since the downgrade I noticed my PH was not stable compared to the bigger tank and was wondering how could I keep it stable? I also was wondering what is an acceptable PH swing range throughout the day.
Calc: 520
Alk: 9
Mag: 1340

 

[Randy Holmes-Farley Verified Community Expert]

More aeration will reduce the pH swing and reduce the pH (if those values are real).

In general, I do not think the swing is very important except as it indicates how well the tank is aerated, and what the extremes hit are each day)

I suspect that unless you use limewater, the pH may not be as high as you see and I’d try recalibrating the oH meter.

 

[JohnBa]

Yea these are my values, and I’ll try the air pump I just didn’t want to get too technical with PH as I read that you’re not suppose to chase the PH but it was stable in my 240 before the transfer. I’ll recalibrate and buy another probe also thanks for the reply

 

[Randy Holmes-Farley Verified Community Expert]

FWIW, I don’t agree with the idea to not “chase pH”, you just need to do appropriate things with appropriate expectations of what will happen as a result. [emoji3]

 

[Dana Riddle]

I observed some extreme pH values such as yours in some of the tide pools isolated from the ocean during low tides (also high temperature and dissolved oxygen values.) When the tides rose, these pools were flushed with 'normal' ocean water and pH, temp, and oxygen measurements quickly changed (dropped.) The corals in these pools (mostly Porites, with a few Pocillopora species and others) were stunted in growth but surviving (reduced growth was probably due to exposure to high levels of light and ultraviolet radiation, where the photosynthetic apparatus within zooxanthellate was damaged and much energy had to be devoted to repair.) I'm not suggesting we should replicate these values, but personally I wouldn't be overly concerned unless the corals are showing some sort of stress response. In addition, corals have a limited ability to regulate internal pH, so the values of the water might not be applicable to them.