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Re: another new tank.....

G Kadar writes:
> Now this individual writes that he puts a layer of "organic topsoil" mixed
> 50/50 onto the very bottom, then three to four inches of gravel.   I know
> that there are others out there who add this as well.  I purchased 88 pounds
> of washed play sand (surprisingly clean and the colour is pretty nice).
> This sand is the easiest thing I have ever had to "wash".  And if I mix it
> up a bit in water, it settles down within seconds!  I also picked up 40
> ounces of laterite.

I see little point in using laterite if you're also going to use soil.
The concepts are mutually exclusive. The important attribute of laterite
(aside from high iron content) is the lack of other reactive elements,
especially the organic material.

If you choose to use laterite, I think it would be best to follow the
guidelines in "The Optimum Aquarium" book or to refer to George Booth's
excellent website for guidelines. This method is effective, proven and
safe.

> Now don't shoot me down folks, my body is still aching from moving furniture
> yesterday.

Sorry! Budda-budda-budda-budda... Ka-POW!

> As of yet I don't have the CO2 system for this tank. Maybe never
> if it grows nicely.  It is sitting beside a window (north-north-west plus
> balcony overhang) so it's going to get light, but no sun, plus flourescents
> on top. Will I have a total unmitigated disaster on my hands if I add soil
> to the very bottom, plus laterite and sand and then lots of sand on top?

You probably wouldn't have an unmitigated disaster but I don't think it
would be a very effective design. Depending upon the composition of the
soil, you could certainly create some noxious problems.

The roots of most plants seldom penetrate more than a few inches into
the substrate. Why do you want a deep substrate? As far as I can see, it
doesn't give you much. Why not add the soil mixture in a thin layer in
the bottom and then cover it with an inch of gravel. I find that sand
simply cannot hold buoyant plants in place during the initial planting.

Soil if used too deeply where the roots cannot penetrate, will go sour
and produce toxic byproducts. Its not ag good idea. I feel that it is
important when using topsoil or any soil mixture which contains organic
material, to plant densely and to provide good growth conditions so that
the roots of the plants can penetrate into the soil. These roots provide
oxygen which helps to prevent strong reducing conditions. Strong
reducing conditions produces H2S, methane and other noxious byproducts
which you probably do not want in your aquarium.

If you really want a deeper substrate, I recommend a three layer
approach. The bottom layer should be sand or gravel or clay or subsoil
or a mixture of those. No organic matter. No peat. No humus. No
fertilizer. A deeper substrate makes it possible to plant certain plants
which come with a long tap root. Alternatively, these can be planted
with the root sideways and allow the plant to grow back into the
vertical. This is a useful trick for getting several offshoots from a
long stem plant like Hygrophila stricta.

Folks who are interested in using topsoil in aquariums would be wise to
review Paul Krombholz's methods using trays. You will have to search the
APD archives or perhaps his recommendations are in the Krib. Other
substrate designs that you find discussed on the Internet, while they
may work and even produce dramatic results, do not necessarily have the
benefit of insight into the biochemistry of substrates.

Steve Pushak                              Vancouver, BC, CANADA 

Visit "Steve's Aquatic Page"      http://home.infinet.net/teban/
 for LOTS of pics, tips and links for aquatic gardening!!!