At our super helpful local Progressive Garden shop, the clerks are usually very happy to talk my ears off about soils, and mediums in general.
You might ask around there, I know I learned more talking with the associate than I had about soils on RIU in a week.
Foxfarm Ocean forest, with all the goodie nutes is a safe bet, and many members on RIU swear by it.
Hope it works out, take er' easy...
LOUNGE; No Seaweed Required!