High PH - Do I need help?


New member
my tank is 1.75 months old. Im having a bad issue with GHA.

My pH swings from ~8.15 to ~8.70. Should I be worried about this? The corals are all opening and growing. I just added a firefish and yellow tang yesterday (only two fish in the tank). im running a carbon and phos reactor. dont seem to slow the algae.

nitrite/nitrate/amm/phos are zero.

cal 500
mag 1500
alk 3.66
kh 10.2

This because of the GHA? Help me out!


New member
pinpoint tester. I calibrated it yesterday. I double checked with a API PH test also. The results look accurate.


New member
I got the fish yesterday and havent fed them yet. Other than that nothing - no dosing.

I have two K3's in the tank(55g). The top of the water isnt moving as much as it should. So I could add anothe k3 or reposition the two?

And this could also be from stale air? Being summer I never open the windows, to its basically ac 10 hours a day.

GHA would have nothing to do with the ph?

Randy Holmes-Farley

Reef Chemist
Premium Member
Some good surface turbulence will help. The fish metabolizing food will also drop the pH. It is not from stale air, but rather inadequate aeration of the tank water. With perfect aeration, there is no pH change in the tank.

A lot of photosynthesis (by algae, for example, or corals) reduces CO2 and contributes to the daily pH swing. But aeration will bring in CO2 and reduce the peak.