Re: substrate Qs

> From: "A. Inniss" <andrewi at u_washington.edu>
> I was thinking of using a substrate
> consisting of maybe 1/2 inch of worm castings and peat, topped by 1/2 inch
> fine gravel, topped by 1 inch of laterite or an iron-rich clay mixture
> (that Steve Pushak found in Calgary? Could you fire that address my way,
> Steve?) topped by 3 inches of fine gravel.  I was also thinking of mixing
> into that first layer the abovementioned KHCO3 and CaCl in order to
> prevent excess acidity in the soil and, of course, to provide K and Ca to
> my plants.  What do my fellow APDers make of this plan? 

1/2 inch of worm castings and peat is TOO MUCH organic material and
too fertile. This would almost certainly lead to persistent green water
problems. I would suggest 5% by weight of either worm castings or
peat mixed with 60% ordinary sand and 35% of the Terra Stone clay.
Also I would use a 1" layer of sand on top of that as a seal and
either pebbles or a little gravel to help hold the plant stems in place
during the initial planting. If you have plants with roots then you
should have no trouble with planting even in sand. I'd add the substrate,
a little water, do the planting, fill the tank and then drain it and
then fill again carefully to avoid stirring things up. Planting tends
to disturb things a little but they settle out quickly enough. It just
takes time. Since we don't know which micro-nutrients might be absent
in the Terra Stone, I recommend mixing some fritted trace elements into
the clay layer.

20 Kg Terra Stone iron rich pottery clay

Cost:     ~$18 Cdn for 20 Kg
Address:  Plainsman Clays Ltd       Phone: (403)527-8535
          Box 1266
          Medicine Hat, Alberta
          T1A 7M9   CANADA

I wouldn't add KHCO3 and CaCl into the substrate. A slightly acidic
substrate is fine; you don't want it to rot. Instead, why not use
some finely ground eggshells. The Ca and K in the substrate are of
little use to the plants. These nutrients must be in the water and
should be supplemented regularly along with Mg at water changes or 
in a daily regimen like PMDD or Dupla drops.

Some one else asked what to do with a green unicellular algae bloom.
You have a few choices:

1) grow a floating cover such as Ceratopteris or Salvinia.
This may require chelated Fe which may actually aggravate your green
water if you have a lot of nutrients in the water coming from a too
fertile substrate. This can also be extremely hard on your other
plants. They may survive but look like twigs with all the leaves
they drop or melt.

2) use a diatom/micron filter to remove the algae. Depending upon
how much nutrients are in the water the algae can grow almost as
fast as you filter it. I like the Hot Magnum but you need about
three micron cartridges to use in rotation.

3) remove ALL fishies and put in daphnia. This method works great
(at least in the small tanks I've tried it with) This may be a
particularly good method to use on a new substrate since you
don't have to add fish intially especially if you took precautions
to avoid introduction of filament algae such as the use of
algae free plants or by a brief bleach treatment.

You should also practice very frequent and large water changes and
decrease the length of lighting time (not intensity).

Also, I would not suggest the use of chelated Fe additions to a
brightly lit tank with a lot of nutrients possibly from an overly
fertile substrate. The iron clay seems to provide plenty of Fe at
least initially. Fe in the water can be just the nutrient your
algae was waiting for. There is a lot of evidence to suggest that
it is iron not phosphorus which is the principle rate limiting
nutrient for algae in aquaria.