Do you notice any ill-effects on your fish and coral when you refill is probably the first question to ask. It's probably not the worst thing in the world, but if you're worried about it, you could always use an auto-topoff system to continually replenish the evaporated water.
I'm working on a 'bucket type' auto-topoff system for my new tank, though I'm sure someone has already invented such a thing. If not, I'll share schematics when I've completed them. |