I like using a UGF along with HOB power filters. I believe the UGF gives me some added bio-filtration. I'm thinking on replacing my gravel with a sand-type substrate when I break down my tank for cleaning. I do not think the UGF will work if sand is poured over it. But, what if I cover the UGF plates with a nylon cloth mesh that won't allow the sand to pass through the holes in the plates? Even if that works, is the sand going to allow adequate filtration with smaller gaps between particles? If I add the powerheads, will that help pull water better and improve efficiency? I kinda think it will and many of you have stated that powerheads are the way to go with UGFs.