Using dirt as substrate

[koi]

Has anyone ever used potting soil as a substrate under an inch of sand/gravel

[mgarrido]

That is Diana Walstad method. Google her name and you can find a lot of information of how to do it properly.

[koi]

Thanks has anyone here ever done it before

[kwc1974]

Hit up davemonkey (he is on this site). What you are describing is the el natural method, Dave knows quite a bit about it and has done several successful tanks using this method.