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My external canisters have been running for six months. Outflow is constant. My internal media is floss and felt with one layer of charcoal impregnated fiber. Need I change the media? I'd expect the flow rate to diminish as/ if the fiber becomes clogged.
-Barry

Hi all,

b.reder wrote: 01 Feb 2018, 23:20My external canisters have been running for six months. Outflow is constant. My internal media is floss and felt with one layer of charcoal impregnated fiber. Need I change the media? I'd expect the flow rate to diminish as/ if the fiber becomes clogged.

Do you have a pre-filter on the intake? If you don't? You almost certainly have "tracking" or "flow tunneling" in the canister filter media <(viewtopic.php?t=19297)>.

This is where the water is flowing straight through the filter, taking the course of least resistance.

The water can either flow around the filter media, or go straight through it on one path (which option will depend upon the filter design).

This isn't great if you are reliant on your filter for biological filtration, because the filter will be working at a tiny fraction of its nitrification potential. If the filter material isn't oxygenated you have the chance that ammonia levels in the tank will rise to toxic levels.

I'm not a fan of any mechanical filtration media inside the filter body, I just want ammonia and oxygen.

There is a discussion of this in <"Using deep gravel..... (https://www.planetcatfish.com/forum/vie ... d&start=80)>.

cheers Darrel

Thank you. I'll be checking on them tomorrow. -Barry

I think this depends heavily on canister and tank size as well as stocking.

Most mechanical filtration involves organic material. In nature, and in certain filters using specific media, much of the mechanical filtration is handled biologically.

I run several canisters. All of them are the Eheim Pro II series. I have different media in them depending upon when they went into service. I am planning to change the media in older filters as well. What I now use is 100% Poret foam. In a 3 basket filter the first basket in flow is 10 ppi, the next two are 20 ppi, in two basket filters they are both 20 ppi.

The fist canister I set up with the 100% Poret (no blue or white filter pads) has been running for about 2.5 years without being cleaned. My other canisters get cleaned twice a year.

I much prefer Matten filters in terms of doing mechanical filtration biologically. This works best when massive amounts of quality media are used. In my pleco tanks utilizing HMFs the water is pretty much as clear or clearer as in any of my tanks with various other types of filters on them.

In nature there is no filter floss

Went through today and changed all four canister filters. Three had evenly distributed brown gunk. No evidence of channeling. One did show areas of virgin filter material. The last tank had four layers of felt and volcanic pomace- as seen in fire pits. None of the tanks were cleaner then the others. All are cleaner now after the media change. -Barry