Hi PHX
GH nurts is good stuff,start at 1/4 of directions on the bottle and build up slowly.Venting hot air is going to be an isue and fresh air too.I would use distilled water,wally mart it's a 6.0 PH.Mix up the nurts in a larger container and let it sit for a few hours stir it Than check the PH.Starting with distilled water at 6 ph you know what nurts will rise or lower the ph.
Keep us posted on the grow.