What’s the highest safe Ph in Acro tank?

[SMG91]

I‘ve been house sitting for a family member while they’re out of the country and my Ph has been reaching peaking and holding about 8.7-8.8 Ph for about 4 hours each day. I’ve been dosing less Kalk and more BRS 2-part trying to offset the ever increasing Ph with the co2 deficiency in the house while we are gone. My tank is all acropora, am I going to return to a dead tank?

 

[SMG91]

On the 17th I stopped by the house to check on the tank (hence the lower ph peak). All my acros looked fine except for my purple dragon eyes and my inferno Mille had very small amounts (about 1mm in diameter) of bleaching on a single branch midway on the branch. For reference, my daily Ph swing is 8.25 to 8.64 when we’re home.

 

[Randy Holmes-Farley]

My best guess is that the pH meter needs calibration.

It is hard to maintain such a pH, and simple aeration with any air will lower it.

 

[SMG91]

The probe is only 6 months old and was calibrated and verified in the 15th of this month. I believe too that these numbers are hard to maintain and could defiently be incorrect, but in case they are true, I am just curious if this high of a Ph is unhealthy for corals.

 

[Randy Holmes-Farley]

The probe is only 6 months old and was calibrated and verified in the 15th of this month. I believe too that these numbers are hard to maintain and could defiently be incorrect, but in case they are true, I am just curious if this high of a Ph is unhealthy for corals.

I have never heard of a tank that could attain pH 8.7 regularly, except in overdose emergencies, so if true, it is uncharted territory.

But since I've literally seen thousands of pH results from folks, that makes it unlikely to be true.

The thing that does happen is magnesium hydroxide and calcium carbonate begin to rapidly precipitate from the aquarium.

Try the aeration test with indoor air. If the pH does not drop a lot, it is not accurate.

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

The Aeration Test

Some of the possible causes of low pH listed above require an effort to diagnose. Problems 3 and 4 are quite common, and here is a way to distinguish them. Remove a cup of tank water and measure its pH. Then aerate it for an hour with an airstone using outside air. Its pH should rise if it is unusually low for the measured alkalinity (Figure 2). Then repeat the same experiment on a new cup of water using inside air. If its pH also rises, then the aquarium’s pH will rise simply with more aeration because it is only the aquarium that contains excess carbon dioxide. If the pH does not rise in the cup (or rises very little) when aerating with indoor air, then that air likely contains excess CO2, and more aeration with that same air will not solve the low pH problem (although aeration with fresher air should). Be careful implementing this test if the outside aeration test results in a large temperature change (more than 5°C or 10°F), because such changes alone impact pH measurements.

 

[Righteous]

The apex pH probe is notorious even when calibrated. Mine typically reads 0.2-0.3pH higher even after multiple calibration attempts. I’d double check it with a second pH meter.

 

[Deep]

Agree apex PH probes are very inconsistent even when freshly calibrated.

 

[Roli's Reef Ranch]

Mine read .2 low relative to the Hanna PH test kit.