Underground filters

I'm not sure I would call it ignorance, as I have spent alarge part of my
life designing large and small filtration units, and have an excelelnt
understanding of fliud dynamics and how filtration works.

In any case, while powerheads can increase the flow through an UGF, a
properly set up and maintained airstone can (and does) provide an excellent
water flow. as an example, in one of my tanks the air lift tubes creates a
little over 6" of lift (this is about average for my tanks). There are 6
lift tubes (it's a 125 gal), so summed together that is a lot of water flow.
Even though a power head may provide a bit more flow, more is not always
better, and I have ben very satisfied with the results at these flow rates.
I have played around with power heads, and unless I ma trying to create a
current in the tank, I don't see any significant advantage.
-JD


"eekamouse" wrote in message
ups.com...
On Oct 9, 1:30 pm, atomweaver wrote:
Tynk wrote
oups.com:





On Oct 9, 7:20?am, "jd" wrote:
Yeah, I can relate with the cleaning of the crud off th e plates, but
I only do that when I'm tearing atank down, which is hardly ever now.
Since I'm not doing commercial or research work any more, my tanks
are all recreational, and I don't have to tear them down unless there
is a good reason. I have tanks that have been going for 6 years
without a teardown, and they're rock solid.....
-JD

- Show quoted text -

As you and RM mentioned...the crud under the plates is my biggest
*con* when it comes to using them.
(Pay no attention JD to the troll tailing me...we are simply
discussing the pros and cons of them and he has to make it into
something it's not...sorry *for* him).
It's that crud that is basically a ticking time bomb. Often an area of
it becomes a toxic cess pool that can release a toxic gas bubble into
the tank.

I'm not big on fluid dynamics, but it seems totally plausible to me that
JD
was holding such a bubble in a static location (a "dead" corner?) under
the
UGF with the flow from his air pump, and the failure of the pump is what
allowed it to diffuse into the tank. THe rapidity with which his water
quality dropped (2 days, IIRC) indicates more than just normal metabolic
action of some fish in a heavily planted tank. JD's story may actually
be
another indictment of UG filters, as that rapid drop in water quality
might
not have occurred if the UGF wasn't there, but I guess not enough is
known
to say for sure.

DaveZ- Hide quoted text -

- Show quoted text -

The biggest problem is ignorance in how and what makes a UGF work, and
unless the bio load is light you need much more than an air pump to
get decent flow under the filter grates. The only way is with a decent
powerhead in place of the airstone or bubblers. Reverse flow works
fine too.............air powered tend to have dead spots, forced flow
(powerheads) do not tend to have dead spots.