"Mr. Gardener" wrote in message
...
On Sun, 5 Mar 2006 11:31:42 -0500, "NetMax"
wrote:

"Mr. Gardener" wrote in message
news
On 4 Mar 2006 17:53:30 -0800, "Frank"
wrote:

David wrote,
Do people find that the manufacture recommendations for their
filters
(ex: for up to a 30 gallon tank) are accurate, or do they stretch
that?

I think the best thing that has happened with filters over the past
40
years is the bio-wheels - they remove DOCs where other hang-on power
filters without the bio-wheels don't. I would however, well over-size
the filter on any fish tank, and on tank of 55 gal. and up, use two
over sized filters................... Frank

Comparing the gph - gallons per hour - of various filters, instead
of
tank size ratings, might give you a better handle on capabilities of
different brands. I compared a few of the popular brands and found
that their rated tank sizes did not always agree in gph. Different
brands might determine that 3 complete turnovers of a tank's water is
sufficient, while another company might rate their filters using 5
turnovers of water per hour. So the hypothetical 30 gallon tank might
be matched with 90 or 100 gph by one brand, but 150 gph by another
brand. Aquaclear and Whisper were pretty consistent, basing their
tank
ratings on 5 tank turnovers an hour. Others varied, sometimes within
a
brand; a rating of 5 turnovers an hour might be used for smaller
tanks
while only three turnovers an hour was good for, in their opinion,
larger tanks. So recommended tank size for a given filter is
subjective and will be forever debated, gallons per hour is a
measurable, objective rating.

-- Mister Gardener

While gph is a measurable number, the _quality_ of the filtration is
better described as (gph x surface area). This is why a canister
filter
for the same tank is at a lower gph (and probably does a better job as
mechanical, chemical and biological filtration all happen better at
lower
flow rates). Other than that, flow rate only describes turbulence
(heat
distribution) and pick-up power. Sorry to rain on your attempt to
simplify things ;~). I think Eric summed it up well. Go big, dial
them
slow and use multiple systems where it's possible.

I didn't intend to recommend filter choices, I intended to provide the
only objective specs that are usually named by the various
manufacturers. I know that I didn't say "more is better", because I
don't believe it myself. Just providing a point of reference.

Yep. There doesn't seem to be any credible common criteria to use when
comparing filter systems. Chemical filtration is straighforward
(supports it or not and how much) and if you really dig you might find
the particle size a filter media will screen to, but how to calculate
'effective' surface area for biological filtration is beyond me.

From a filtration view, your big TetraTec is multiple systems, but
since
it only has one motor, one pump, one intake and one serial flow path,
then from a system's view, it has no redundancy, so it's one filter
(your
fish are one snail shell in the impeller-well away from stress ;~).

My Tetratec is not the only filter on that 55. It is supplemented by
another power filter at the other end of the tank which is rated at
300 gph, in effect, sized so that if either filter goes down, the
other will be able to carry the full load. Both filters are dialed
down somewhat, the rates being changed from time to time to provide
good circulation for the plants which are all growing at different
rates as they begin to get established.

I was justing using your TetraTec as an example. I know you have
multiple filters on that tank. I tend to post in generalizations for the
benefit of others who are investigating topics. Sorry for the confusion.

My strategy : use 2 or more filters, each capable of at least 75% of
the
tank's requirements, and alternate their cleaning.

Which is what I'm running. And how I'm maintaining them. Once again, I
think the original thread was about comparing manufacturer's claims
for power filters, not about the quality or placement of various types
of filtration.

Yep, just generalizing ).... but quality & quantity is part of the
formula. Manufacturer's claims tend to be adequate for a normally loaded
tank with proper maintenance, however this set-up tends to be a rarity
;~).
--
www.NetMax.tk


-- Mister Gardener