Calvin and Hobbes just LOVE their fountain. They drink ALOT more than they used to. Makes keeping up the box and additional challenge but it's worth it to know their bitty bodies are being flushed out more regularly.
As to changing the water, I do it about once a week. The fountain is in the kitchen on a linoleum(sp) floor and though I sweep and sweep there is always kittyfur tumbleweed blowing across the floor. The water eventually gets fur in it even though I would have hoped the hair would get trapped in the filter and I could just rinse it off rather than changing the whole thing.
In addition, I think if you use filtered water when first filling it might help. The few times I've filled it from the tap, I noticed the next time I cleaned it there was a residue on the bottom..not gross just slippery.
Think I 'll try putting a rug under it to catch the fur before it become water-bourne!