Hi all - I was wondering, my canister just doesn't seem to be doing the filtration job I expect - mechanical, that is... How often should I change the fine and coarse filters? I was under the impression that I should only rinse them so as to save the bio-filtration living in the pad... but I do have a large layer of Ehfisubstrat - bioballs type substrate... so, so the pads actually have to be replaced?

I am using an Eheim 2215 (Classic) canister in a 20g tank with two (large) fish in it - no plants, no gravel. THANKS!

Hi Graham



Since you are using a bio-media in the canister, you can rinse the pads off as often as you like. You can even do so under the water pressure from a hose sprayer or handheld showerhead The chlorine hitting the pads is of no harm to your fish as you will dip them in dechlored water before adding back to the filter.

Even though there IS a small amount of beneficial bacteria growing on your pads, the entire population of beneficial bacteria will be in/on the bio-media, exclusively. Just keep rinsing the pads off at least once a week and this will begin to happen.

In fact, doing as I described above will reduce the amount of nitrAtes that rise in the tank between waterchanges. The regular removal of the rotting debris stuck on the pads cuts off the excessive production of ammonia thus nitrItes thus nitrAtes. Also, this reduces the amount of KH/pH drop between regular waterchanges as the acidic process of the nitrification cycle will be reduced.

All in all, you want the ammonia being expelled by your fishes gills to be the main source of ammonia, not rotting debris on the filterpads..........


I hope that helps explain it in better detail!

Whoa! It most certainly DOES explain things in better detail!



I think this excatly the problem, now that you have articulated it so well...
I have been having a nitrAte problem - which also accounts for GN's floatiness!

I will do this immediately! I think a difference will be noticed - I will follow up!