# Clay



## dusted (May 1, 2011)

I was going to try a dirt tank sometime down the road. What is the difference between grey and red pottery clay? The only clay I only know of around here is from walmart.
http://www.walmart.com/ip/Amaco-Moist-Gray-Pottery-Clay-5-Pounds/12347700

or could i use crushed clay pots?


----------



## colisalalia (May 17, 2011)

I am a newbie researching. 

I came across this article. They use red clay. As I remember it adds more nutrients. I think the easiest thing to do is call any local artist that does ceramics. They have huge trash bins of clay that has dried up. I can't imagine that they would charge you. It is trash to them, and loads of it.

http://www.aquaticplantcentral.com/...-mineralized-soil-substrate-aaron-talbot.html

Christy


----------



## RickRS (Dec 31, 2010)

The red color is from iron oxide, aka rust. It provides the plants with a source of iron so dosing for iron is not needed, or at least dosing need is reduced. Gray or white clay could be usable for substrate, but not as desirable because the iron content is much, much, lower.

I've thought of using crushed pots, as well, but those are fired, which binds clay and prevents the iron from being usable. Dried raw clay will turn into a slick mud when wet, something clay that has been fired won't do.

And lastly, in the past I emailed Amaco, the supplier for the clay in your link, to asked about modeling clays found at craft chain stores (AC Moore and Michaels are two in my areas). Some are synthetics clays and I was trying to find if the stuff available locally was or not. Amaco's tech support warned that some of the natural clay sold for modeling clay have preservatives and they would advise using it as substrates for aquariums. Two they ok'ed were Sedona Red 67S (not stocked at any local store) and Magic Mud (stocked, but a white clay). Why preservatives for what is essentally dirt, I have no idea.

I wound up using some terra cotta clay my daughter had left from her college pottery art class.


----------



## dusted (May 1, 2011)

I was guessing they would add some kind of chemicals in it, everything has preservatives now. I will just use the dirt in the backyard garden, it shouldn't have any fertilizers in it. I think we have quite a bit of iron around by me since every rock I find has rust on it.


----------



## kamikazi (Sep 3, 2010)

come to the Piedmont of NC, you can did up some clay from my yard.


----------

