Ph

cactusreef · May 19, 2026

Hello.
My tank ph is sitting just under 8 (7.8-7.9 hard to tell with colors). Is this an issue? The tank is a few weeks old, will it come up on its own naturally? Should I supplement something? Is my test faulty? I’m using API.

ShakeyGizzard · May 19, 2026

A lot of your parameters will change back and forth as your tank matures, steady maintenance and water changes will help keep it stable. i tend to go by the parameters below. As far as your PH at this time its ok

Quietman · May 19, 2026

I wouldn't worry about pH at the beginning and it's really never a great idea to chase pH numbers. API isn't terribly accurate but it does give you a ball park trend. Just under 8.0 is acceptable. Take pH first thing in the morning before lights come on to get lowest value and a couple hours after lights go out for the highest. That'll give you your band.

If you're in a closed house/room, opening the windows can help some as CO2 builds up in homes that are closed up. Other than that, just let it go for a while and worry about it when you have money for better pH meter for accuracy and have higher end corals that might benefit from maxing out some parameters.

Fish Fan · May 19, 2026

You're fine. The pH will fluctuate at times especially when your tank is new. But I know a lot of very successful reefers here on R2R that don't check pH at all. I know tanks that run at about 7.8 chronically, and they are fine. I would suggest worrying about keeping your pH up only if you're growing corals professionally or competitively.

If it helps, carbon dioxide in the water (from animals respiring) will form carbonic acid, which lowers pH. Ensuring that you have good aeration in the tank helps to keep the pH up by allowing the carbon dioxide to leave the system (and oxygen comes in). Additionally, if you have the windows closed and a lot of people and pets, the air around the tank can be high in carbon dioxide. Opening a window to allow fresh air to the tank can help. Many refers will literally run a hose from their protein skimmer to the exterior of the house, so that the skimmer is pulling in fresh air from outside the house.

I wouldn't try dosing a liquid pH buffer product, I think it would be more trouble than it's worth, and likely result in an unstable pH. I believe steady and a little low is better than a constantly fluctuating pH.

Here's Randy Holmes-Farley's article on pH where he discusses why it might fluctuate, and a simple 'aeration test' to check for excess CO2:

pH and the Reef Aquarium - REEFEDITION

by Randy Holmes-Farley For many aquarists, pH is not something that they have much experience with aside from their aquarium. For many, pH is almost a black box measurement: something to be considered, but whose physical meaning makes little sense to them. This article will Read more here...

www.reefedition.com

I hope this helps!