Thu, 18 May 2000 23:31:52 EDT

The major problem with UGF is lack of maintenance. These filters work just
fine as long as you keep up with the gravel siphoning etc. The other way they
can work with a little less maintenance is to run them with the power heads
set for reverse flow. This way most of the particulate matter doesn't choke
the filter bed. If you have an undergravel that hasn't been maintained then
take a flashlight and look up through the bottom of the tank. All of that
junk (aka, mulm, detritus) can cause the undergravel to function at less than
optimum ability with a corresponding loss of water quality (usually low
alkalinity, pH).
If the gravel bed becomes too clogged then the possibility of anaerobic
bacterial growth becomes a possibility. The problem with anaerobic bacterial
growths is the possibility of hydrogen sulfide release into the water and the
possibility of fish death.
Hope this clears things a little,

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