I had the opposite experience of the one taslixado desribes.
My substrate consisted of worm castings mixed with pumice and laterite. I boiled the castings exactly as the origianl Brazilian site suggested.
The top layer was about 1 inch of inert gravel.
I checked the P and N in the water right after filling up the tank as well as in the course of the next few weeks. They were always 0.
10 gal tank, 2.6 wpg, KH=2-3 and pH = 7.0.
The tenellus, Hygro polysperma, and the Java Fern in that tank did not grow at all for about 3 months (at which point I tore the tank down). Granted I had too little CO2, but there was no growth whatsoever in that tank. I don't know what to think because the plants developed good roots.
Uprooting did not raise the N or P.
--Nikolay |