well first of all ditch the distilled. it possibly cant be any better then what's coming out of your spicket. the test strips will be the best investment you make, 10 bucks or so and it can make huge difference. and if it needs adjusting you will have to shelf out the money for ph up or down. 10 bux

only foliar feed in the dark cycle.. or what I do is pull them out of the grow box, mist them with the finest mist i can get, let it soak in a little, and shake em to remove excess


and like stealth said, keep the lights as close as possible..