Clay Pots

> From: Neil Frank <nfrank at nando_net>
> > From: Erik Olson <olson at phys_washington.edu>
> > I've read somewhere that bricks and earthenware pots are basically laterite.
> > Could one "produce" aquarium laterite by smashing up some red clay pots?  
> This idea was mentioned in the past, and was even published in TAG 
> (during 1991), so it can't be that stupid :)

Well, I could be stupid for not remembering the article.

> The TAG article was by a Ph.D. soil or horticulture scientist. If it 
> works, then the clay is not attracting stuff because of its small size, 
> but instead because it is providing something (like iron?). If the latter 
> is true, then why smash it up into small bits -- to provide more surface 
> for contact with the water?

I would grind or cut up laterite because

	1. It would more evenly disperse the stuff throughout the 
substrate instead of localizing it in one place.

	2. It won't cut off water circulation the way a full pot does.

	3. As you say, more surface area.

	4. It's fun to break stuff.

> While searching for interesting aquarium substrates at sand and gravel 
> places,  I recently came across a huge mound of what looked and felt like 
> laterite.  It was crushed red brick.  Since all I wanted was 25 pounds, 
> they did not know how to change me.  I have used it in several tanks, but 
> like other "experiments" the results are not very revealing. The plants 
> are doing good, but this is the case in all my tanks :)

Same deal with my pseudo-laterite Lake Shasta clay.  It looks good.  The 
plants do well, the substrate's clear detritus as George predicted.  
Can't disprove it.

> I also had the stuff tested by the dept of AGriculture.  It does not have 
> the same chemical makeup of the red clay here; one surprise was that it 
> does not have pH < 7.

That could be bad.  Maybe brickmakers add calcium carbonate to the mix?

>  I do not have the results handy; I will try to 
> remember to post them another time. (but I may need to be reminded)


[Neil continues...]
> What do people think are the advantages of the clay pot (over plastic)?
> One possibility is that they are porous, so may reduce anaerobicity 
> (maybe good, maybe bad).

Not much.  I've had stinky potting soil come out of both plastic AND
clay pots.  But I certainly had been conditioned to think they "breath" 

> Another possibility is that the material provides some benefit to the 
> plant or to the aquarium  (see Erik's question about clay pots 
> and laterite).  Do they absorb stuff which is good for the plant? or 
> improves water quality?

Heh heh.  I had a horrible disaster happen to me due to a clay pot: 
someone sold a whole bunch at a local aquarium auction.  Little did I know
the blessed absorbant containers were chock full of chemicals (pesticides? 
medication?  who knows...), which promptly killed every fish and most of
the plants in the tank I stuck one in.  This was even after washing it
off.  Plastic has no such effect.  Plastic pots are also less tapered, so
they waste less space when you're trying to cram as many as possible into
the tank.  You can also get square-base plastic pots.  And they're 
cheaper.  AND you can get them in the same reddish color as clay.  And 
you can drill holes in the sides if you're worried about them breathing.

I think it's an ol' wives' tale. :)

  - Erik

Erik D. Olson					olson at phys_washington.edu
Not at home, probably at work (Wo-hoo!)