Canister filter on RSM?

[Coralgurl]

I run a canister filter and clean it out with each water change (a complete scrub of the inside every 2 weeks) and clean and change the media monthly. This has been working fine up until recently, but I did change the filtering media and wonder if this is contributing. I need to buy the stuff I was using before and see what happens. As long as you maintain them, they are great!