[fish_4_all]

Honest question, I am not making light of anything more than trying to find the places and circumstances where they are not only viable but recommended. My experience with them is a simple nightmare and that is over 20 years of using them off and on with both airflow, powerheads and a combination of both.

I also have a question about reverse flow:
Where does the actually filtration happen in reverse with an UGF? Do the powerheads need filters? Does the gravel and plates act the same as they would using them in the "standard" fashion? Do you have to have another filter to act as a mechanical filter with reverse flow.

 

[herefishy]

In using powerheads with reverse flow, a sponge filter acts both as a detrtitus filter and a bio filter. Yes, the gravel bed does act as a bio bed, but not in the traditional means. In traditional setup of the powerhead, the gravel bed serves two functions, (1) as a detritus trap and(2) as a bio bed for bacteria. The sponge filter is attatched to the intake side of the powerhead trapping particles before they are ingested by the pump. Water is then pumped beneath the filter plate. Air can be injected at this time to help provide your bacteria in the gravel with o2 by opening the venturi of the powerhead. The reverse current helps to keep most detritus suspended which is why I use multiple means of filtration. Only the heaviest particles fall to the bottom. You notice I said heaviest, not largest. By using multiple filtrations systems, water quality is better, water clarity is better. The fish are happier, I am happier. I truly have less upkeep. No weekly water changes, and, in most cases, no monthly water changes. The BIG tanks might get a water change semi annually.

Something many may not even consider here, any object in your tank, ei, decorations, stones, rocks, gravel, ect, is a part of your bio filter system.

 

[fish_4_all]

Ok, that explains the reverse part.

Now what type of tank setup works best for this?

 

[herefishy]

I would say tanks up to 55g, depending upon bio loading. Bio loading is best described as the amount of waste generated by your fish and your feeding habits(wasted food / do you overfeed.). My 29's are all running multiple filtration systems. Bio loading is high. If you have a 55g tank with 15 neons, 6 hatchet fish, 6 cories, and 6 serpae tetras, bio loading is low. However, if you have 6 chocalate orandas and a 10" plecostomus, bio loading is probably high.