I've never had an UGF, but it seems as if it's main source of filtration is the gravel. If UGF's were used successfully in the past, then does that make gravel a good supplementary filter for a tank? If you have 4x turnover with commercial filters, then in a best case scenario it still takes 15 minutes to filter the entire tank volume once. With gravel across the entire bottom of your tank, wouldn't that aid greatly in removing very small amounts of lingering ammonia and nitrite that are not being pulled in by a commercial filter?
Does gravel or sand have more surface area? I would assume sand has much more surface area because of finer grain size, but gravel has gaps which allows water to seep efficiently. Even if sand is stirred every week or two, it is still much more compact than gravel and might prevent water flow through it...does that limit the filtration capacity of sand? Note that I am only talking about aerobic bacteria.
I like sand for aesthetics but black sand is out of my budget, and the bucket of black gravel I have laying around wins in cost and color(vs play/pfs IMO).
I know there is a sticky on sand vs gravel but I don't believe this was covered.
Does gravel or sand have more surface area? I would assume sand has much more surface area because of finer grain size, but gravel has gaps which allows water to seep efficiently. Even if sand is stirred every week or two, it is still much more compact than gravel and might prevent water flow through it...does that limit the filtration capacity of sand? Note that I am only talking about aerobic bacteria.
I like sand for aesthetics but black sand is out of my budget, and the bucket of black gravel I have laying around wins in cost and color(vs play/pfs IMO).
I know there is a sticky on sand vs gravel but I don't believe this was covered.
