Any ideas about low pH?

[sphelps]

A low pH won't typically cause issues but the thing with corals is they can usually handle one or two issues without concern but add a third and you could be in trouble. Just like in the wild the increased amount of CO2 is lowering the pH but it's not until other factors including elevated temperatures are added that the reefs become really vulnerable.

So although a low pH isn't a huge concern it will make your reef more vulnerable if you experience temperature or lighting changes. It's also a pretty easy fix with Kalk which will also precipitate phosphate so a win, win situation. Just always remember to make changes slowly.