It looks a little like nutrient burn to me... but i'm a total n00b, so don't take this as your final answer. If they were my plants, i'd either weaken the solution even more, or just feed it straight water for a week or so.

...keep in mind thats just what i'd try, not saying it will help at all.
Faddenator Reviewed by Faddenator on . NEED HELP WITH LEAVES Hello everyone I have here 9 plants there OG cross with purple kush that i purchase from Ontario Seed Bank. The plants are 26 days old and I having an issue with the leaves. I'm using tap water with a mild solution of Dyna Grow the label says use 1/2 Tsp per gallon my Res is 20 gallon. That would be 20 Tsp for 20 gallons I only use 15 Tsp im not sure if that the problem my leaves have gold and brown spots but the new growth looks fine and also I'm having leaf curling. The PH is around 5.5 Rating: 5