Under Gravel Filters

NotCalebSherida

AC Members
Nov 3, 2004
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1) how do these work?
2) what kinds of substrate can you have with them?
3) do they clean out the substrate from debris/excess food/etc.
4) can they support heavy rocks?

thanks :dance
 
Umm, they dont!

No I`m kidding they basically create a biological filtration cycle in your tank but I find they dont work very well and your fish are more prone to disease. I would recommend having a undergravel as well as a power filter. They also need a slightly larger sized gravel to work properly large rock is generally fine.
 
I have one in my 29 gal and now wish I hadn't put it in there. Will be a major hassle to take it out at some point. Seems to make vacuuming the gravel more difficult. Next tank for me - no UGF
 
I used to use nothing else other than the UGF (say 20 years ago) but they are a hassle and all the sludge gets sucked to the bottom and after a while you can't move anything without crud everywhere - and generally I guess you need a lot more maintainence than what I was doing at the time. When I set the tanks up this time I didn't go that way. Part of that was I wanted a very course gravel bottom to simulate the local rainforest creeks and the plan was to have rainbows and a couple of other local fish that like to live in the gravel... I managed to get some of those gravel dwellers but no rainbows yet, so the rest of the tank is tetras and such... But I digress. The UGF was a great biofilter idea I guess, but a wet/dry (or canister I dare say) does it better, and the above tank wet/dry setup I use is so much easier to maintain and it collects the big crud in the prefilter and keeps the tank cleaner... Gets the crud out of the tank rather than collecting it up on the bottom rotting and such... Easy to remove, rinse the poly matting, etc, rather than cleaning the gravel...
 
You still need to clean the gravel in unplanted tanks regularly and rountinely. That chore is not escaped regardless of the biofilter.

Prefiltered RFUG does not build up waste inthe gravel bed.
 
Sand will be siphoned out with a vaccum if you push the vaccum into the gravel. You can wave it over the top and capture most all solid wastes easily, but it does take some practice. The sand will migrate some--how much will depend on how much digging the fish do. If the gravel is exposed, you will need to vaccum those areas deeply, but if the sand and gravel are mixed well enough, this will prevent solids from working down much.
 
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