"Eric" wrote in message
. sbcglobal.net...
On Sun, 11 Sep 2005 08:13:35 -0500, NetMax wrote
(in article ):

"Eric" wrote in message
. sbcglobal.net...

[My data on filter flow rates deleted]


My understanding is that biological filtration works better at the slower
rates of water flow. Note that water flow is not directly 'changes of
tank
water' due to the different filter media area surface. Canister flow
rates
are typically slower than powerfilters *and* they have more filter media,
so
the biological activity is much much better. When comparing flow rates,
compare powerfilters against powerfilters or canisters against canisters.

I agree about not being able to compare powerfilters and canisters solely
by
flow rate. That's why in the interests of saving time I just decided to
leave
canisters out. I also agree that the quantity and type of filter media
makes
a big difference. The Penguins and Aquaclears have a lot more going on
with
them than the Cascades and Whispers media-wise.


The real use of tank-changes (the typical x4 to x5 rates you saw) are to
keep a uniform temperature and to aid in the mechanical pickup of
detritus.

And I don't see how going for more than 5 tank changes per hour would aid
in
mechanical pickup unless the tank is packed full of poop-machines like
large
goldfish.

Applications where there are a lot of rockwork, like mbuna tanks benefit
from higher flowrates to get between the stones. This is also where
canisters are better as you can better direct the flow, though powerfilters
generally have higher flow rates than canisters.

Generally, between filtering correctly and over-filtering, you should
over-filter, for no other reason than fish grow, eat more and multiply.

I agree, though I go more for combining different types of filters than
using
one big filter.

) Absolutely !!
--
www.NetMax.tk


-E