Re: terrapur cones

Neil Frank asked about Terralit cones, if they were similar to laterite.
I told him I figured they had clay but I didn't know what else; probably
a nutrient mix of some sort. The color is light brown (not red).

> Thanks for the info on the cones. I have never seen any of Aqualine. Bu.'s
> products. I am so skeptical of such things, unless I know something about
> the people who promote their use.

I checked, it's Aqualine Buschke. A guy here in the office has a small
aquarium and I've given him plants for it. He uses the cones at my suggestion
too. The plants only get window light but are doing ok. Nothing fancy.

> >We don't have any sources of laterite in stores here.
> >I suppose I should be ambitious and create my own using potter's
> >clay...
> I agree that this may be equivalent, but I am lacking good data on how to
> decide.
> I basically wonder about the similarities/differences among potters clay and
> laterite. I have heard that there are many types of potters clay, each with
> different ions (incl. metals). Do you have any information on how to choose
> a particular clay and what treatment if any is needed (e.g. short duration,
> low temperature kiln firing)?

I am skeptical about the supposed superiority of laterite over other
cheaper substrate schemes. (IMHO) Nobody has given a strong scientific
explanation about why it would be better than ordinary soil supplemented
by Flourish for example. I'm not disputing that laterite is a useful
substrate additive; there's a heck of a lot of empirical evidence
to show that. People have mentioned two things about laterite:
1) better algae control (I have some theories about that but not much
discussion here about why)
2) long term stability. (why? I need a better understanding of this)

Before this thread takes off on a laterite vs. soil theme, that's not
my point here. I'm sure there are lots of substrates that work well
and they all share a lot of similar properties. I think we should 
focus on those properties to understand why they work.

Clays or soils cause the plants to develop root hairs and much 
larger root systems than plain gravel. Clay & soils have good CEC.
Soils are sources of carbon, chellates, Fe and several other nutrients.
I also can't see much difference between clay with or without Fe if you
either supplemented with chellated Fe regularly or added Fe to the 
substrate such as steel wool or iron oxide. Paul Krombholz has given
me an excerpt of the TAG article on soil explaining how insoluble Fe oxide
is reduced to a more soluble form in the anaerobic environment at 
the bottom of a continuous soil containing substrate. (ie. under 
gravel filter plates would prevent this beneficial recycling of Fe) 

I have been very impressed with the results of first soil/vermiculite 
substrate (short term albeit). I attribute that to soil rather than 
vermiculite. I think in future I would try it without vermiculite 
and with composted manure.

I should think that clay is clay except for Fe content. If you had potter's
clay with high Fe, well, you would have more Fe wouldn't you! If you
were setting up an aquarium, I'd mix soil and composted manure for the
bottom layer (not too much water to avoid a cloudy tank) and cover with
a good layer of gravel. I'd probably add ground egg shells and a small
amount of steel wool to the soil too. Same as Paul Krombholz's recipe
just add Fe. I figure that composted organic plant material (like
bovine manure) has all of the correct elemental building blocks for
plants approximately in the correct ratios (after all, it was once
plants, eh?)

For an existing tank, I'd mix the clay into small balls and dry them.
You could assist the drying in an ordinary oven but definitely don't
fire them in a kiln. That would destroy all the good properties of it.
Then you could just shove the clay nodules into the substrate. You
could also grind up and mix some fertilizer tablets with the clay.
I have not made my own clay nodules but I think it's a worth while