It doesn't seem like i can upload in the hardware forum, and i have no space of my own, so making a thread here related to this thread.
So here is a picture of the sponges (specifically, replacement "foam inserts" for Hagen Aquaclear filters) used in place of the cartridge in Eclipse systems. You can also buy the sponge in bulk chunks at some LFS, and you may be able to find it packaged for other filters as well. The pic is of the largest (i think) Eclipse system, but the same principle can be applied even to their smallest systems, you'll just have to cut the sponge to fit.
At each water change, rinse one of the sponges in discard tank or dechlorinated water, alternating at each water change. Or you can rinse both if you put a lot of faith in the bio-wheel.
I used the sponges in the pics for years and never had to buy replacements, it worked much better than the commercial or homemade cartridges and is lots less work. I don't use the filter part of the hood anymore though, switched to a canister, which is why you can't see the Eclipse pump unit in the pic. 
Hope this is useful to some of the other Eclipse owners.
Edit: yuk i should have cleaned it before i took pics, sorry!
So here is a picture of the sponges (specifically, replacement "foam inserts" for Hagen Aquaclear filters) used in place of the cartridge in Eclipse systems. You can also buy the sponge in bulk chunks at some LFS, and you may be able to find it packaged for other filters as well. The pic is of the largest (i think) Eclipse system, but the same principle can be applied even to their smallest systems, you'll just have to cut the sponge to fit.
At each water change, rinse one of the sponges in discard tank or dechlorinated water, alternating at each water change. Or you can rinse both if you put a lot of faith in the bio-wheel.
I used the sponges in the pics for years and never had to buy replacements, it worked much better than the commercial or homemade cartridges and is lots less work. I don't use the filter part of the hood anymore though, switched to a canister, which is why you can't see the Eclipse pump unit in the pic. Hope this is useful to some of the other Eclipse owners.
Edit: yuk i should have cleaned it before i took pics, sorry!
