Re: dead tree leaves in aquariums

> From: Stephen.Pushak at hcsd_hac.com
> I think leaves would inhibit circulation in the substrate and if
> buried, contribute to anaerobic decay conditions. Decaying material
> in the substrate greatly increases the oxygen requirements of the
> substrate and drastically alters its chemical and biological
> composition.

When Fabio D'Alessi wrote the 2 part article for TAG a year or so ago,
he was careful to use specific leaves.  Apparently, when deciduous 
leaves do their autumn thing, most of the nutrients are pulled from
the leaves by the tree before they drop (and hence the color change). 
This type of leaf will not readily decompose and will not contribute
nitrates, etc to the water.  The idea seemed very good except for what
I imagined teh appearance might be. The leaves provide hiding places
for fry and extraneous beasts and make a natural setting. I beleive he
is/was a biology grad student in Italy and had carefully researched
the concept. 

> George, even with the laterite granules, don't they recommend a
> layered approach? When I looked at T.O.A. pictures in the early days
> of laterite, it sure looked like they were using a very clay-like mud,
> red in appearance.

It's layered in the sense that 1/3 the gravel is mixed with the
laterite and put in first, then the rest of the gravel.  Since the
laterite has high iron and is very red, it turns this lower layer a
different color.  That's what you're seeing in the photos on page 56
and 57.  The lower layer may look dense and compact, but believe me,
it's not.

> Anybody else have any comments about alkaline and/or anaerobic
> aquatic plant habitats?

"Dynamic Aquaria" has a large section on this. Most mud-bottom lakes
and streams are anaerobic below the first few millimeters.  Nature
takes advantage of this very well.