HELP!! Filter media question...

[carsona246]

+1 on the quilt batting. I would just go with that idea and use the plastic frame to hold the polyfiber in place. I use the polyfiber in walmart without a problem for my canister filter, and it's like $5 a bag and it lasts me a while. That being said I don't think I ever switched out my HOB cartridge unless the water wouldn't flow through it, which took forever. I'd just rinse it really well in old tank water, and it used to last for months

 

[SCGeordie]

The cartridge in your pic is easy to adapt/change to bio media, I've done it on a couple of mine - just pull up the plastic 'clip' in the centre at the top of the cartridge and the plastic 'sides will come apart releasing the top of the white foam 'bag' empty out the carbon (easiest under a running tap) and then replace with something like substrat pro (Eheim?) works great.
Alternatively you can just leave the carbon in, once it has lost it's effectiveness as a chemical filter it still works as a 'home' for beneficial bacteria (although not as good as the substrat pro). I do that with whisper cartridges, the two 3i's I have on my 6gal have had the same cartridges in for 4 months now, just swoosh them around in tank water each week, I've never had an ammonia or nitrite reading above 0 since the tank was cycled.