Chim (and others) Contamination Control have very nice filter bags you just hang them, great for exactly what youre talking about
"Steve's tip of the week"
Hey Mr Evil I agree totally as long as they dont get slack its a great idea even my new AP902's have the drain tap on the cup but i wouldnt use it myself as i know i'd get a bit complacent.
I've always wondered whether this was a possability.... New tank..smear a layer of siicon over the base with a wallpaper scaper then sprinkle with sand, kind of like mixing sand with paint to stop people assing over
Would this be a go???