Using kalk water only for topoff?

[BCOrchidGuy]

I'm assuming you aren't testing for Ca, you should, the calcium test kit isn't expensive and it can give you an idea of where your calcium levels are at. Remember too that live rock will use some calcium, actually the coraline algae will use it, and if you use strong actinic light you may be surprised by how much coraline algae growth you get.