Never heard of using black lights. Methinks that's a bunch of crap. I think your problem is with the ferts. I never used any ferts at all until mine started flowering. If you want to give them some nutrition, get some worm castings from a nursery and mix those with the soil. MJ loves that shit. I never had a ph problem doing it that way. (It stayed right at 7 through the entire grow.) I would only introduce a small amount of fertilizer (with a high middle number) during the flowering stage, and even then I used it very sparingly. (Also, be sure to allow a couple of weeks before harvest to flush the plants with pure water - you don't want to be smoking Miracle Gro!)

As for lighting, during the vegetative stage (1st two months) use "blue light" (6400k lights) 24/7. During flowering, (last two months) use "red light" (2700k lights) 12 hours on/ 12 hours off. After four months, you should have some really awesome, aromatic buds (depending on the variety).

For ventilation, keep a fan running the whole time to circulate the air.

Hope this helps - Good luck!