So, the 3 SCH are doing great, JF clones are 4.5/6, although entirely my own fault. I left the zip on main tent down and one of my cats was investigating the rickety scaffolding in a strange very bright white room, and was really surprised to be suddenly showered with wet substrate and small plants... Luckily only one clone was a outright write-off, the .5 was just kinked, so I masking tape splinted and it seems to be ok. You can see it in the middle below. the idea is to keep them all in main tent, until there's something to flower. Then I'll get around to setting up my smaller tent for mothers/vegging.
Talking about substrate, the grow medium I use is largely recycled from previous grows, with top ups of whatever it seems to need, including lots of home-made compost. I've seen advice to not recycle, but i've never had problems, and it spends a long time 'ageing' outside in the sun between re-uses.
Nutrients; at the moment it's just water for everyone, substrate has enough nutes to get through until 2nd transplant. When I do start, I have been using Green House Feeding powder fertilizer. When that's finished though i'll be switching to their BioGrow version.