Re: Power filters to RUGF (or RFUG?)

["S. Hieber" <shieber at yahoo_com>]

Andrew McLeod asked:

> Is it possible to use a power filter, such as a Fluval 3
> Plus, for example, 
> to power a reverse undergravel filter, or is the pump
> insuffucient? But if 
> it was not powerful enough, could the power filter be
> used as a mechanical 
> prefilter (with fine filter media as an extra in a Fluval
> 3 Plus), and then 
> a powerhead drive its output through the UGF to allow a
> small power filter 
> to drive a tank of a large capacity than its rating (due
> to the increased 
> biological filtration)?

Generally, the answer is yes.  An aquarium substrate bed is
such a large filter medium that it doesn't offer an
excessive amount of resistance to a pump.  But substrates
with UGFs or RUGFs tend to clog up over time and that can
eventually slow down the water flow substantially.  If you
have lots of plants, the clogging will be mitigated by root
activity, the buildup will also be mititgated by the
plants' use of nutrients.

In a well planted tank, a mild flow through the UGF/RUGF
might be better overall than a high flow anyway because a
high flow isn't needed since a lot of filtration isn't
needed in a well planted tank and very little water flow is
needed to keep the roots happy (after all tanks with no UGF
grow flourishing plants and tanks set up with substrate
heaters provide very very gentle flows, which by reputable
accounts is choice).

A ggod idea, imo, if using UGF/RUGF for biofiltration is to
get as much mechanical filtration going on as possible
outside of the substrate to prevent impaction of the
detritus.  With a UFG/RUGF, ideally you're not trying to
build up a lot of mulm -- it shouldn't be necessary since
you're putting your nutrients to the roots via the water
circulation.

If you're using a power filter to feed an RUGF, you can
occassionally check the rate of water flow  by rremoving
the siphon and seeing how fast the power filter is emptied.

Hope that helps,
Scott H.

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