you can get a ph test kit for abot 5 bucks at any pet store! don't harvest your ww's at 5 weeks. i always let mine go at least 10 sometimes even 11-12. ww gets better the longer you flower for(within reason) i am pretty sure it is ph prob. as well. i don't uderstand how people can get through a whole grow without testing ph. i tested ph of the water/ferts every time i gave anything to my plants. most fertilizers are way to acidic and after mixing up the fert solution the ph must be raised back up to around 6.4 with ph up before it is givin to the plants. also if you add 1-2 tbsp per gallon of dolimite lime to the soil when mixing it, you will have much more stable ph throughout the grow. a must if using a peat based mix imo. good luck!