Originally Posted by Myates
Lots of info flying around.. the link is going to be your best bet on how often to clean the tank you have. You can clean too much and cause health problems with your fish down the road, just as if you hadn't cleaned enough.
On a side note- water conditioners work instantly so there is no reason to keep water out for any length of time. As long as your conditioner takes care of ammonia, chlorine than you can just go straight from tap. Try to make sure the temp is roughly the same as the tank's temp to help reduce much fluctuation.
+1 Definitely read the link before anything else. Too sterile an environment, i.e. 100% wcs everytime, is not good for your fish either.