well, being that you don't have enough live rock, i would be wary to tell you to just keep them changed, but that's what i'd do. i change mine to new ones whenever they get bad, just to eliminate the nitrate factory arguement. it's costly, but worth it to me. i have rinsed and reused before, but find they don't last very long before they are clogged again. but i have enough live rock in my opinion to provide enough bacteria so i try not to rely on the filter for that, because i like to keep it clean so it works better. and also i don't run the risk so much of disrupting the system whenever i do clean it. because to me, if you cycled your tank with just live rock and powerheads, and no mechanical filter, the tank would "cure" enough to the point to sustain itself, and you would only need the filter to remove the solid waste that floats around in the water. i worry that i filter out good things, so i'm trying to rely on the (skilter) as less as possible for my biofiltration. this is just my thinking on the subject, whatever you decide to do is up to you, but if you only have your filter to provide biofiltration, then you are always gonna upset the balance by changing any of your filter media in my opinion. damn, did i just type all that!