pH 8.5 to high???


New member
I just checked my pH and it was bouncing between 8.4 and 8.5. Am I getting to high? Should I take any kind of action now or should I just watch it for a day or so? Also how high is to high?


NTTH Rookie Help
Premium Member
mine is at 8.2 but some reefers have theirs that high and their tanks still thrive, perhaps you should re-post this on the chemical thread, randy and boomer may help more

Randy Holmes-Farley

Reef Chemist
Premium Member
IMO, that is not too high. I recommend 7.8 to 8.5 and preferably 8.0 to 8.5. Mine runs 8.35 to 8.5 each day, typically.

This article has more:

The "How To" Guide to Reef Aquarium Chemistry for Beginners, Part 3: pH

from it:

What is the Acceptable pH Range for Reef Aquaria?


The acceptable pH range for reef aquaria is an opinion, rather than a clearly defined fact, and certainly varies based on who is providing the opinion. This range also may be quite different from the "optimal" range. Justifying what is optimal, however, is much more problematic than justifying what is simply acceptable. I suggest that the pH of natural seawater, about 8.2, is an appropriate goal, but reef aquaria can clearly operate in a wide range of pH values with varying degrees of success. The pH of highly successful coral reef aquaria often deviates substantially from pH 8.2 for at least part of the day. In my opinion, the pH range from 7.8 to 8.5 is a acceptable for reef aquaria, with several caveats. These are:

That the alkalinity is at least 2.5 meq/L (7 dKH) and preferably higher at the lower end of this pH range. This statement is based partly on the fact that many reef aquaria operate acceptably in the pH 7.8 to 8.0 range, but many of the best examples of these types of aquaria incorporate calcium carbonate/carbon dioxide reactors which, while tending to lower the pH, also tend to keep the carbonate alkalinity fairly high (at or above 3 meq/L.). In this case, any problems associated with calcification at these lower pH values may be offset by the higher alkalinity. Low pH stresses calcifying organisms primarily by making it harder for them to obtain sufficient carbonate to deposit skeletons. Raising the alkalinity may mitigate this difficulty by supplying extra bicarbonate to them.
That the calcium level is at least 400 ppm. Calcification becomes more difficult as the pH falls, and it also becomes more difficult as the calcium level falls. It would not be desirable to push all of the extremes of pH, alkalinity and calcium at the same time. So if the pH is on the low side and cannot be easily changed (such as in an aquarium with a CaCO3/CO2 reactor), at least make sure that the calcium level is acceptable (~400-450 ppm). Likewise, one of the problems at higher pH (above, say, 8.2, but becoming progressively more problematic with each incremental rise) is the abiotic precipitation of calcium carbonate, resulting in a drop in calcium and alkalinity, and the resultant clogging of heaters and pump impellers. If the aquarium's pH is 8.4 or higher (as often happens in an aquarium using limewater), then it is especially important that both the calcium and alkalinity levels be suitably maintained (that is, neither too low, inhibiting biological calcification, nor too high, causing excessive abiotic precipitation on equipment).