Re: Filter capacity

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

Bill Wichers pointed out that:

> Hagen's AquaClear hang-on-tank filters have adjustable
> flow rates. The 
> mechanism is very, very simple (the intake tube can be
> slid over the pump's 
> intake so that the pump pulls less from the tank and more
> from the filter 
> box), but it does work. You can reduce the flow maybe 5-6
> times normal with 
> them. For a lot of media at a low flow rate they are
> probably the best way 
> to go since you can also fill the media compartment with
> three foam blocks 
> instead of the foam/carbon/amorid stack if you want. I
> presume most of the 
> canisters can also be set up this way, and maybe also
> flow-reduced with a 
> valve, but I haven't tried it.

Indeed a simple and adjustable setup.

To this I would add that any aquarium water pump or filter,
at least any one that uses a centrifugal pumping mechanism,
which is most on the aquatics market, can have the output
throttled down if you put a petcock or ballvalve on the
output line.  You can even pinch the output tube with a
clamp, although that's pretty clumsy to adjust and the tube
might eventually crack at the stress points as it ages and
hardens.  Throttling down the output won't hurt the pump
although it might slown down the revolutions a bit and
slightly increase the operating temperature.  Since the
impeller can still spin, even with the water flow
substantially blocked, you're not going to get an excessive
draw of amps nor excessive heat.

Those hang on back filters are rather easy to clean/change
out media.  Otoh, a large canister can go for months and
months without needing a change.  A wet/dry/sump setup,
with a nonclogging medium can go indefinitely without
needing the medium cleaned.

Scott H.

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