Check at the El Natural
section in APC forum. I have tanks set up with dirt for I liked the idea that many only change water 1x a year and don't dose ferts. My water is excessively treated thus have to change 1/3 monthly. Couldn't find the 3ml gravel needed to keep the dirt down so used play sand. Then tried pool filter sand (PFS) and then river sand. I like the river sand the best. It is brown and doesn't get dirty. I found it at a landscaping co. a 50lb bag for $3. I used Scotts top soil. It has a lot of mulch in it that needs to sifted out. Read someone got some dirt with very little mulch at True Value hardware store.
The Amazon plants tend to outgrow even a 30 gallon tank. The micro sword needs iron sulfate via API root tabs
. I don't think it will stay in the big rocks without the cotton. Usually people take it out and spread it out.