400 gallon project

[Delphinus]

Wow, that does seem high. IMO though, in and of itself, the number shouldn't cause you concern if the livestock appears otherwise healthy and happy and whatnot. Ie. I think people tend to focus too much on things like "Oh no! My tank's pH is 8.1 and everyone else is at 8.4, I should add some pH up or something" - which is folly because the pH itself is only a summation of other variables at play. And of course, if the tank is doing fine at 8.1 then one shouldn't worry about it not being 8.4.

But, I have to say I'm a bit surprised to see those numbers if you're running a calcium reactor. I thought running a reactor tended to pull the #'s downwards. For example, on any tank I run, typically I see pH swings around something like 8.1 to 8.5 without a reactor on a tank, and about 7.8 to 8.2 when there is a reactor on the tank.

Sooo anyhow I have no idea what to make of your #'s, that is interesting indeed, although like I said if your livestock is otherwise doing fine I wouldn't sweat it too much.

Maybe because your tank volume is so large it has an easier time shedding any excess CO2 from the reactor?