[mcintosh]

They are good filters when used correctly, Marcie (how is that for a lead-in! I love waffles!)
I have both and have used them to filter freshwater planted tanks. They work great in that application because they provide a large surface area for bacteria to work their magic in and they can be cleaned regularly (read every month). Of course you don't want to remove all of the bacteria so I rinsed the filter materials in tank water that had been removed for a partial water change. This is also a good time to change the carbon and phosphate remover in your filter.

That being said, in a reef tank, you are constantly battling Nitrate issues in the tank. Any excess Nitrogen in the tank will allow problem (undesirable) algae to take over and outcompete your (desired) corals. The theory behind live rock is that the bacteria within the rock convert nitrate to nitrogen gas through denitrification. The same can be said with deep sand beds. If you find that your nitrates are uncontrollable you may want to consider leaving the rings and the filter floss out of the canister filters. Unless you are religious about changing (rinsing in fresh RO/DI water would work) the filter material every week.

HTH