> Subject: Laterite balls/shards: low surface area
> I don't understand ANY benefit to fired clay (other than it can provide
> the same benefits that a gravel substrate may provide). Having been
> fired at 1100+F, the iron is lost. Even if it were there, virtually all
> of it is inaccessible because we now have a "stone" with a very LOW
> surface area/volume ratio.
> It seems much simpler to distribute the laterite around the substrate
> in its smallest (manageable) form: More surface area is *readily*
> available to rootlets, it is more distributed so more rootlets can be
> accommodated over the same cubic inch of substrate, and circulation
> is (potentially) improved at the actual rootlet bonding site.
I can see no advantage to the use of "ball" shaped laterite when setting up
a new tank. As you've mentioned, the smaller the particles, the more
surface area, the more available to the roots. I _do_ think, however, that
it can be used to advantage in an existing tank to improve substrate without
a total tear-down... And I don't personally know anyone who has gone back to
a straight gravel substrate once they have tried laterite in their
> I'm not sure how well it weathers over time, though. If you start
> with 2" balls of laterite and a year later you have a 6"x1/4" patty
> of clay (to be extreme), then maybe larger is OK: we will get the
> surface area simply because time will make it so.
Having dug up areas containing laterite balls, I can tell you from
experience that they do, indeed, spread out. In fact, In my tank with the
UGF/heater system, if you take a flashlight and look under the tank, you
will see a layer of laterite completely covering the entire bottom of the
tank. So it has obviously moved through the substrate even with the
extremely gentle currents created by this system.