Most of the quarries in this part of the country produce limestone-based
gravel. This is fine as long as you don't need to have a soft/acid water
chemistry for your fish. That's where the Red Flint is superior. There is
at least one quarry in Ohio that produces a silica gravel, but I have found
that this material constantly produces a fine grit that will wear out
moving parts such as impellers in powerheads and powerfilters.
I use UG filters almost exclusively. I have found that the size of gravel
that is useable is limited by the size of the slots in the UG filter
plates. If the gravel is too fine, it will leak through or cause them to
be blocked. The other issue is water movement and clogging of the filter
bed. Obviously, fine material will restrict water flow and clog faster
with solid waste. I have actually used fine silica sand over a UG filter
by wrapping the filter plate with panty hose fabric. This worked OK, but
over time, the sand and fabric became clogged with solids and was
dangerously ineffective at biofiltration. I use the 1/8-1/4" Red Flint in
most of my tanks. I use the 1/16-1/8" in tanks with eggs or hatchling fry,
all with UG filter plates. The 1/16 is right at the limit where the plate
slots will start to become blocked.
http://jonahsaquarium.com/tankdeco.htm
Mark
Columbus Ohio USA <))><
mbinkley_at_columbus.rr.com
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