I have a type of lava rock in my tanks. A guy collects it in the tablelands in the tropics{inland Cairns} He drills holes in it etc. It is not light like pumice, so is used by most as part of there display in tanks.
He basically supplies the whole of QLD with this. He has had people do set ups with marine fish where this lava rock is the sole bacterial filtration. I have used these in my tanks as display.
Once while doing a change around I took a few big pieces out of one of the tanks, guess what, ammonia spike. I use these now to help cycle new tanks. No change to tank ph etc.
Point being sorry, pumice is way more porous, if you can get a hold of some of that cheaply that will go good in filters.
http://en.wikipedia.org/wiki/Pumice
Ceramic noodles are good, the rough ones are better than the smooth ones. I use these with a mixture of matrix.
I know of people who use onion bags in their sumps, scourer pads & the like. They all work well.
If you are using a sump, dacron is better than filter wool. Holds shape better, easier to replace & holds more waste too, therefore changing less.
Tip for canister filters is to use coarse foam instead of the fine stuff{dacron, filter wool} that way they act as bacteria growers as well & still catches most particles. Lasts longer too & you don't have to clean as much being the main advantage.
Frenchy