Brown spotsey spots, dying leaves

Hello,

I'm growing DWC and had a few problems early on with light getting to my roots and nutrient burn. Since then, my plants look much better.

However, on some of the older leaves there are strange brown spots appearing on them, from which the leaf dies around. Also on some other leaves the leaf has grey spots.

I am using GH 3 part flora, 3 - 1 - .5 ratio. I am using tap water with a PPM of 150 with aquarium grade chloramine/ammonia/chlorine eliminator, with nutrients my PPM is about 360 right now.

30 gallon reservoir, nutrient solution stays at about 65F. About 70 - 75 in my room, sometimes 80 during the day, low of 60 at night I think. 25% humidity usually, trying to increase.

All the seeds are from mid-grade bagseed strains that particularly liked over a year. Think I'm growing 3 different ones right now, but possibly only 2.

pics are from 36 days old.


I try to keep my PH around 5.5 but after a few days it usually raises to 6.