I'd go with a reverse flow UGF--if the substrate is gravel. The water welling up through the gravel will keep the solid wastes suspended longer, allowing the filter to trap it. You might want to add another filter that will be purely mechanical filtration, and put a sponge on the intake of the whisper to prevent the solid wastes from getting into the media. This way, the solid wastes are easily removed and the biological filtration is undisturbed.
Probably the best solution would be to get a gravel vacuum and suck it all up when you do your water changes. Filters like that aren't able to clean the bottom too well.
Many of us have to deal with this issue with "poop machine" fish. Heck - even some small livebearers can be like that. Anyway, gravel vacuums work wonders. I use it every 2 weeks thoroughly, and all of my tank’s bottoms are what I consider clean.
If the poop bugs me, or there is too much floating waste when the fish stir up the bottom, I'll just lightly siphon the bottom and replace the water I took out.
Just as I use to pass my vacuum every other day or so when I had rugs, I suppose. I don't like dirty floors
i have a 8 inch pleco so sucking up poop at least every other day has become a religion here.if i don't the whole tank would be covered in poop in no time
The best thing I can recommend is a gravel vaccum one or twice a week to remove the waste and water changes. If you don't have a gravel vaccum you can get one at Wal-Mart or a Pet supply store and are very inexpensive and will probably find that a clean, new 5 gallon bucket comes in handy when using the gravel vacume to clean your tank. Hope this helps!!
I just stir it up with a turkey baster, and let my prefilter sponges catch it. however, years of experience have caused me to settle on a natural substrate which is very much the same color as pleco poop. From a few feet away, the poop is invisible.
Dave