I heard alot of guys saying no nutes for seedlings til week two or three..... it was always my thoughts to go with 200 ppm and gh three part.... is that about what you did? is the medium like small hydroton?
Unlike some people i started my grow in soil then i transferred the seedling to the Ag.
Now before i did the transfer i used the nutrients on my seedling so it could get use to the medium and the nutrients in the AG.
I find even using Advance, its not too strong for the plant to handle even at is seedling age.
So to answer your question My medium was soil i got from Kmart
Now god forbid this does get to big for the A.g (which i doubt ) i have a 5 gal container that i can transfer to and make it a soil closet grow .
Yes i have changed from soil to hydro
and hydro to soil
and what is the deal with hydroponic rocks