Re: NANFA-- anyone ever toyed with this idea?

Joshua L Wiegert (JLW_at_dune.net)
Mon, 19 Jan 2004 12:01:39 -0500

I hadn't thought of malaysian snails -- they'd be an ideal addition to help
keep the sand stirred. However, if all you're interested in is the
additional biological surface from the plennum, I'd suggest buying a Merlin
or another commercial sand filter. These are neat little devices that are
essentially a column with two nipples on the top. Water goes in one nipple,
out the ohter. Inside the column is a super-fine sand, much finer than what
you'll be using inside the tank. This sand is blown up by a pump, which
keeps it constnatly stirred, providing a huge surface area. You don't get
anaerobic decay, but... (I suppose if you really wanted to, you could hook
up a dentrifying unit to do that.)

A plennum is basically a deep sand bed. It provides a surface for bacteria
to grow in. By slight disturbances in the upper layers, usually by animals
(in saltwater, starfish, cucumbers, gobies, etc.) you get an aerobic
surface area where bacteria grow, break down wastes into ammonia, ammonia
into nitrite, nitrite into nitrate. By letting the underlayers get
anaerobic, you get an area where dentrification (e.g., nitrate into nitrous
oxide and nitrogen) occurs. Ideally, you therefore have almost always no
nitrogenous wastes. The idea is something of an old fashioned reef-keeper
idea. WIth the advent of high quality skimmers and better filters,
especially wet dry filters, most people have stopped using them. They're
still popular in certain areas and among certain schools of thought....

In freshwater, we have a big advantage over SW -- plants. In a heavilly
planted tank, ammonia should be taken up with minimal competition to
bacteria -- as a result, you'll keep teh nitrogen-waste levels quite low
anyhow.

Its also important to point out that this does not eliminate the need for
water changes.... although yo uwon't get high nitrate, other chemicals will
build up in the water over time which need to be removed by water changing.

JW.

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Joshua L. Wiegert
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