Clay or mud substrate?

[Tokis-Phoenix]

Well i have finally found a new house and its just a matter or getting the money through and the current people living there moving out so i can move in, so i am one step closer to getting my 200gal tank and other tank projects going now so i am increasing the amount of research i am doing on my future tank projects, in particular biotope tanks.
I found an excellant site for setting up all kinds of biotope setups and it mentions alot having clay or mud substrate in alot of them;

http/fish.mongabay.com/biotope.htm

I also found a site earlier for creating a rice paddys and i am now realy interested in re-creating a small rice paddy in an old 3ft tank of mine but it also mentions using clay or mud substrate.
I figured that you can't use any old dirt lying around and dump it in the tank, so where can i get hold of safe clay/dirt to buy or find it? My main concern is pesticides and fertilisers in the soil...
Also, has anyone had any experience in having tanks with dirt substrate of some sort in them? My first worry would be water quality and cycling problems with soil in the tank, but surely in the wild in lakes, ponds and rivers and stuff nature finds a way around this so fish can live in such conditions.
Im so used to removing dirt/waste in my tanks as soon as i see it, how would i go about maintaining a tank thats supposed to have dirt in it? What algae be a major problem with clay or mud substrate?

Thanks for your time and any info/comments are greatly appreiciated

 

[annka5]

A former work colleague from a while ago kept a tank with a mud substrate. She composted plant matter herself, using a worm-composter (company called "wiggly wigglers do these, not sure of web-address, but name stuck in my mind!!). She was really careful about what she put into it, using things she had grown herself and therefore KNEW were organic.
I'm not sure how / if she cleaned the substrate - the water was slightly murky at the bottom but not much.
I don't think cycling would be much of an issue as the filter would develop a good bacteria colony which should be enough to compensate for fewer bacteria on the substrate -thats my opinion, not based on experience of this colleague, though!!
It sounds like a really interesting project, am only sorry that have lost touch with the lass i knew who kept a tank with a mud /compost base.

 

[Tokis-Phoenix]

Thanks for the info , do you think it would be worth boiling up the mud in a saucepan for a bit before adding it to the tank just in somthing nasty grows in it?
If normal dirt is ok i might just dig up some from a feild with cows or somthing grazing on it as the farmer won't use pesticides or chemicals on animal grazing land in case they get sick themselves from consuming it or is this a bad idea?

 

[phishluvr]

A while back I came across this tank setup. It may offer some insight and you can probably contact the owner directly for more info.

Cool idea!

http/www.malawicichlidhomepage.com/spinelli/spinelli9.html

 

[Tokis-Phoenix]

Cheers for the link, i had some realy nice tanks in it too

 

[annka5]

Am really not sure about using mud from grazing land, as farmers will use wormers and antibiotics and the like in the cattle feed. However, I guess these things must leach out into domestic water supply anyway... am just guessing.
I'd be tempted to boil it if it makes you feel better (and it would reassure me) but am not convinced there'd be any "science" beind it!!
The only indirect experience I've had was my former colleague with the compost heap, so am a bit wary of giving advice on the rest of it!!!