NetMax, will this work for me?

[John >]

http://www.tetra-fish.com/catalog/category.aspx?id=126

Do you think this will work for my big tank? Think it will be as noisy as a
swimming pool filter?

JOhn ><>

[humBill]

Untill the 'guru' appears I do have two smaller ponds and an opinion. 'Da
boss' may well show up and say just the opposite of me - in which case I'm
sure his suggestions are best. As I recall you have quite a distance to
push your water. In the absence of numbers on that page I would be dubious
as to whether it has the head to push that distance and have much flow rate
left at all. Many of these storebought filters are essentially biological
filters. The coarse filter mats are primarily to catch large clumps of dead
algae, leaves, poop and the like. Of course, there are the high dollar bead
filters. Even then, I believe sparkling clear ponds will usually have a lot
of floating particulates, compared to an aquarium. My first guess would be
this might work for you biologically. Many ponders would just make their
own bio filter with say a 5000 gph mag pump. My knowledge wanes even more
at this point but I would say an additional large Rena or the like(by the
tank of course) might be called for to really get your water clear and allow
for chemical filtration. That's my story and I'm stickin to it:)
Bill

"John ><>" > wrote in message
...
> http://www.tetra-fish.com/catalog/category.aspx?id=126
>
> Do you think this will work for my big tank? Think it will be as noisy as
> a
> swimming pool filter?
>
> JOhn ><>
>
>
>

[NetMax]

"John ><>" > wrote in
message ...
> http://www.tetra-fish.com/catalog/category.aspx?id=126
>
> Do you think this will work for my big tank? Think it will be as noisy
> as a
> swimming pool filter?
>
> JOhn ><>

I'm battling the flu, so I hope my response will be more clear than my
thinking currently is. Pond filters do not equal aquarium filters in
several regards, all related to fish-load. We talk about tank exchange
rates of between 1.5 and 5 volumes per hour (avr =2.5). Typically, pond
filters are spec'ed in at an exchange rate of 1/2 volume per hour, so
when looking at the amount of water they claim to filter, divide the pond
claim by about 5 (more if you are overstocking). This means the PF
1500's pond rating of 1500g would actually be around 300 aquarium
gallons. The PF 1500 also uses a very small pump (9 watts) which I'm
surprised even achieves 750gph. This suggests that if you stray from
their optimal installation, by using thinner diameter pipes, more elbows
etc, that you will quickly lose power. There is a lot more flexibility
in optimally locating a pond filter than an aquarium filter, so they
might be intolerant of moderate flow resistance.

The PF 4000 puts you in the right ballpark at 800g, but please note that
math is an early victim of the flu, so double check all my figures.

You might have noticed that what I've actually done is re-rated the
filter's biological capability by extrapolating their 'filtering claim'.
It's much more accurate to re-rate based on the cc's of filter media, but
they don't give that specification (nor did a google search reveal
anything else). Generally, pond filters have more pumping power and less
biological capability than aquarium filters, so if you match one, you
will be way off on the other. Pond filters don't have the same ammonia
load to deal with (imagine the bacteria coated surface area of the bottom
of a pond), and the smaller the media openings are, the more quickly the
filter can clog (especially at high flow rates, and the types of debris
you find in ponds).

If I haven't completely lost you, this is where the trade off begins.
With pond filters, when you re-rate them, you generally get 1) a high
flow rate (in your case 5x), ii) a more appropriate amount of filter
surface area (the purpose of the re-rate), iii) a too porous filter media
(which can usually be easily changed), and iv) a very fast flow per cc of
media (the source of your trade off). Bacteria are lazy buggers and they
don't want the ammonia zipping past too quickly. Sometimes our own
design constraints and incompetence will put enough flow restriction to
slow everything down, but in a new well-thought-out installation, you
might get those very high flow rates, which would be disadvantageous.

When I was in the trade, the solution was simply, use the filter baskets
from the larger models and the pumps from the smaller models, and you had
an aquarium filter :~). However, the right way for a purchase is to
calculate the flow rate per cc or cubic inches of media. This is usually
not practical without specs but a comparative analysis between the 3
filters would probably be helpful. However did you notice that the silly
buggers at Tetra marketing used the same picture for all three models?
Let's assume a media fill diameter of 12" common to all models, so with
their respective heights of 15.5", 19.0" and 22.0" (I sub'ed 1' of
plastic for top & bottom) and assuming a relatively rectangular shape
(cylindrical might be better, but I'm flu-math challenged enough right
now), I get:
PF 1500 @ 750 gph / (15.5*12*12) = 0.336 gph /cu inch
PF 2500 @ 1250 gph / (19*12*12) = 0.457 gph /cu inch
PF 4000 @ 2000 gph / (22*12*12) = 0.631 gph /cu inch

(I'm trying to document exactly what I'm doing so my mistakes will be
cuickly quaght ;~).
I took the diameter from http://www.pond-o-mania.com/Tetra_filters.htm
and sub'ed 2" for flow around the sponge.

You can see how the flow rate per cu-in increases non-linearly with
filter flow rate (this is a bad thing). Note that this doesn't take into
account depth of media, different types of media etc. It's pretty crude,
but based on the numbers, I'd say that a couple of PF 2500 should do the
job nicely. Individually, they could carry the load temporarily (your
redundancy) and together they put you at 1000g filtration. Ordinarily
you would aim for 125-150% of your filtration requirements, but I
disregard this guideline with filters which have a backwash capability.
By performing regular backwashes, you remove lots of solid wastes before
they dissolve back into the water, where they are more difficult to
manage.

I wouldn't trust the PF 1500. For comparison, some very efficient
canisters, the Eheim 2213 (103gph) is rated at 8 watts (or 12.9g/w) and
the 2215 (135gph) is rated at 15 watts (or 9g/w), so for the PF 1500
(750gph) to be rated at 9 watts (or 83.3g/w) would be an 'interesting'
achievement. There are many other variables such as hose diameter,
length, number of elbows etc, but it also suggests that this might be an
empty filter rating, which is less useful for planning purposes.

Incidentally if my gph/cu-in numbers were anywhere near accurate (which I
doubt) then even the PF 4000 flow rate is not too bad. Poor biological
filters typically clock in at much higher flow rates. While I was poking
around, it seemed like pond-o-mania had the best prices. Do tell them
about your application. That the filter is pressurized is good, but you
need to know the operating height spec.

As for noise levels (safely assuming my opinion is that of someone who is
relatively clueless), I would suspect that the Tetra filter would be much
quieter. The best is to hear them operate and see if they meet _your_
noise threshold. The 2nd best is to compare noise measurements (in
decibels), if the tests are done in a similar fashion (ie: same distance,
same floor material). The dB meters are very useful for comparisons (and
relatively cheap to purchase), but they average the noise power to a
built in preset filter (ie: dBA), which may or may not accurately
correspond to your personal threshold, mostly due (I think) to the
resonant frequencies generated by the objects in contact with your noise
source, and any noise spikes in the spectrum (ie: 4kHz gives me a
headache). Trust me, if I haven't already put you to sleep, I can
easily drop you on this topic ;~), so if you are concerned, go listen to
the filters and decide yourself.

I apologise for my wordiness. I just scrolled up and realized my flu has
become verbal-diarrhea, so this is a good place to stop.
--
www.NetMax.tk

[humBill]

"NetMax" > wrote in message
...
> "John ><>" > wrote in
The PF 1500 also uses a very small pump (9 watts) which I'm
> surprised even achieves 750gph.

Max - I suggest this is the humblest way, but I think your fit of flu
delirium kept you from deducing that the 9 watts is probably the strength of
the UV light.
Bill

[NetMax]

"humBill" > wrote in message
. com...
>
> "NetMax" > wrote in message
> ...
>> "John ><>" > wrote in
> The PF 1500 also uses a very small pump (9 watts) which I'm
>> surprised even achieves 750gph.
>
> Max - I suggest this is the humblest way, but I think your fit of flu
> delirium kept you from deducing that the 9 watts is probably the
> strength of the UV light.
> Bill


Ha! ..you might be underestimating my ability to screw something up, but
you're most probably bang-on regarding the UV lamp.
thanks Bill.

I just now read your post. Quite right about these pond pumps having
nebulous flow ratings. Some of the better ones at least show the drop in
flow as a function of head. We used to subtract 100gph for every inch
up, and for every inch of waterfall width, just as a quick calculation.
Lots of times the remaining flow was not even positive ;~).

A comment on your biological vs mechanical filtration attributes. From
my understanding, the characteristic of catching organic matter actually
falls under 'mechanical' filtration. Also the removal of visible
particulates comes under mechanical. Biological filtration is the
'warehousing' of the nitrifying bacteria to remove ammonia, nitrites and
even to some extent nitrates. Your description and advice were bang-on,
but the I think that the conventional description would be that they are
poor biological filters and only coarse mechanical filters. The
attribute to make them better mechanical filters (better water polishing)
is a tighter weave of sponge media, which also has more surface area,
more bacteria and is a better biological filter.

thanks again for shedding that UV light on me ;~)
--
www.NetMax.tk

[John >]

> A comment on your biological vs mechanical filtration attributes. From my
> understanding, the characteristic of catching organic matter actually
> falls under 'mechanical' filtration. Also the removal of visible
> particulates comes under mechanical. Biological filtration is the
> 'warehousing' of the nitrifying bacteria to remove ammonia, nitrites and
> even to some extent nitrates. Your description and advice were bang-on,
> but the I think that the conventional description would be that they are
> poor biological filters and only coarse mechanical filters. The attribute
> to make them better mechanical filters (better water polishing) is a
> tighter weave of sponge media, which also has more surface area, more
> bacteria and is a better biological filter.

Thanks for the info. I sent eMail to Tetra and asked some of those
questions yesterday. I have not received an answer yet, I will forward it
to the group when they do. Your detailed answered is well taken, as I learn
more about this obsession we call a hobby, I have picked up an several
things including who's opinions weigh in.

You brought light to what I probably was avoiding, hoping that I found the
magic (filtering) pill. I will continue to work on the 80 gallon trickle
filter I am working on. 40 gallons of bio balls & 4" of mechanical
filtration with 30 gallons of reserve space for emergency power outages.

Thanks Again
JOhn ><>