used it forever successfully -in small doses(short answer)

Long Answer! but be careful! I once harvested some wicked awesome looking sticky that didn't really burn, just charred black:wtf:- from overuse of phosphates(in this case). if my memory serves me :-]

A Simple and cheap nute method for soil. Fert amounts are somewhat strain and environment dependant, and are usually determined by alot of trial and error.

Any decent soil, add 20-30% perlite
Use MG 20-20-20 for veg, Give small boost before putting in flower.
In flower: use trace amounts of 20-20-20 to taste 2 weeks +-
then use MG BB to taste for whatever you think is good for the strain
Supplement with small amounts of Kool Bloom sometime in second half of flower cycle - it stops stretch so not to early

buy alfalfa bricks in pet/farm store, put some in a sock occasionally and let it soak in your water overnight for application on a non-fertilyzer watering

also use an occassional pinch of epsom salts(non-fert watering) and monitor your ph.

Just one method of many, all ferts are readily available at the hardware store except KB which you will have to hunt down.:rastasmoke: