People do this all the time, using an osmolator to push fresh water through a KW reactor. It's no extra strain on the pump as it's still sitting in plain water.

But, if something goes wrong and the pump sticks on, you'll be REAL sorry. It's a risk...the tunze system is known to be pretty reliable, but I decided to bite the bullet and get a medical dosing pump. This way there's absolutely no chance of overdosing KW into my tank.