Originally Posted by i3k
I think 50% a week is perfectly fine, as long as you don't vacuum all the gravel every single water change. That will vacuum out a lot of the beneficial bacteria.
No offense, but I totally disagree about the gravel vacs. More is better with PWCs, 50% is a good amount. The bacteria is predominantly in the filter media. It needs high oxygenation. Substrate can house some, but removing the detritus and rotting food is more important than worry over bacteria loss from gravel vacing. JMO