[Spick]

I've been running my reef tank for 4 succesful months now, and my friend recently informed me, he read up on filtration, and filtering your water with a cannister filter can harm corals. Meaning if your cannister contains a sponge, carbon and "white rings", the collected bacteria could be harmful to the corals. Is this true or somewhat true? Should i take out everything in the cannister and simply put a peice of LR in there and filter it that way along with my protein skimmer? Could someone please inform me if they know what I am trying to get at? Thnx!

[Samper]

I don't know anything more than what I've read. I've never used one cause every since I got in the hobby I've read that they are sort of outdated.
Sorry I can't be more helpful than that.

[apantale]

Hello,

I have not had any issues with cannister filters being used in a Marine environment, and this would be my second year using one. I previously had a Magnum 350 on my first tank, and now my second tank has a Rena XP2 running on a 35Gal tank. I do intend to go Wet/Dry on my next larger tank, but I have yet to see any of my corals perish because of its use, although I can say that I have never used any beads, bio-balls or stars as a form of biological medium. I leave that up to all of the variety of live rock, good water quality and a good skimmer. With that said, I have been ok so far. I did have one issue with a torch frag dying, but that was because there was an issue with it before I got it..

[Spick]

So what was in your cannister filter then? nothing ... just a sponge? you mention you dont use bioballs beads or what not. what do you use inside the cannister?