is Potassium required for reef???? Help??

[sphelps]

I have the same test kit but I never found it that difficult to read, I think lower concentrations may be harder to read as they are whiter but once you get it up to around 350 to 400 you may find it much easier to read.

I use Zeovit K-Balance to supplement potassium but since I use RBS it rarely drops below 350.