I've had a 25 gallon tank going for two and a half years now with less
than an inch of crushed coral. The tank happily houses a 6" diameter
BTA, a 4" diameter rose BTA, a few sexy shrimp, a coral banded shrimp,
some colony polyps, a black long spined urchen, three clowns, a royal
gramma, and temproraily a baby blue tang (which will be moved into my
100 gallon tank when he gets bigger). The tank regularly reads 0
nitrite and less than 5 ppm nitrate.

The tank is an Eclipse system 3, with a hood that has been retrofitted
with a 65 watt power compact light (50/50 10000k/actinic). I also use
the bio-wheel that is built into the hood, though I know many will
claim the bio-wheel leads to high nitrates. In my particular case that
doesn't seem to be true. I don't use a skimmer.

The only problem with this setup is that it grows green hair algae. A
lot of green hair algae. I do water changes every two weeks (20%) and
usually spend about twenty minutes picking algae off the rocks with a
pair of big tweesers.

I do have a deep sand bed in my 100 gallon tank with 55 gallon sump,
but really only because I wanted to house a sand shifting starfish and
they require pretty deep sand. The starfish does a fantastic job
keeping the surface of the sand looking clean, whereas my crushed coral
in the 25 gallon tank is rather brownish.

I'm pretty sure the algae growth is due to excessive nutrients in the
water as I feed the anemones rather large chunks of shrimp or scallop
every other day to compensate for the rather weak light. I'm
considering upgrading to a 96 watt T5 system (my research indicates
that this is roughly equivilant to 130 watts of power compact) and
replacing the bio-wheel with a prism skimmer. I have no plans to
deepen the sand bed.

I think that the reason the tank works is probably due to the algae.
Algae can complete the nitrogen cycle just like the anerobic bacteria
in deep sand beds can. I have a bit of macro algae growing in the tank
and every time I harvest some of the green hair algae it gets a bit
bigger. Hopefully eventually the macro will be the dominant one and
inhibit the growth of the hair algae.

Another way to avoid needing a deep sand bed would be to have a bunch
of live rock in areas in the tank were there isn't much water
circulation. The main thing is to have areas where anerobic bacteria
can live. This means having areas of the tank where the water does not
contain much oxygen. In a deep sand bed the water two or three inches
below the surface of the sand doesn't have much oxygen in it, which is
why it supports anerobic bacteria which do the job of converting
nitrate in to good old harmless nitrogen.

Hope you were able to gleam some useful information from this long
winded reply. Best of luck!
Blake.


wrote:
Hi,

Anyone have an opinion on the next best alternative to a DSB? I just
don't like the appearance of 4" of sand, or 2" for that matter. No
offense meant--I know most of you use this method. But I've had a 30
gallon FOWLR with 3/4" of crushed coral and a canister filter running
for 10 years with zero nitrates, so I don't see the value of a DSB for
me.

Now that I'm upgrading to a larger tank, I would like to replace the
crushed coral with a thin layer of some type of a finer grain sand for
the sake of appearance. Or should I just stick with what has worked
for me? Or maybe, mix the two. Any suggestions?

Thanks,

Grant