Just chiming in about super soil vs. Doc Bud's kit. I never used neither, but if I use potting mix I prepare two separate ones for veg and flowering. The latter one is only used for plants which hasn't been outplanted straight in the soil. Super Soil can be a little too unbalanced as I understand it and be too rich for indoor growing. Doc Bud does lab testing on the other hand and it's really hard to beat that as that's what pros do. He says that potassium causes main problem in homemade mixes usually and the same applies to Super Soil as I understand. Then, it really depends what you use. I don't use any commercial soil for example, and basis for my mixes is always compost so rich in nitrogen that my plants sometimes do not get yellow at all. But I was putting potassium anyway in form of wood ash and never had any problems. Didn't measure brix though, maybe next season. The thing is that you need plenty of potassium for vegetables and I guarantee that as I'm an ardent gardener. It influences number of flowers, size of fruits/vegetables, and their taste! That might be different with cannabis though, but then I never had any problem with taste of my plants. My concern has been mainly about binding nitrogen during flowering, and this season I added more carbon like flower petals and shredded leaves to the mix in order to force plants to suck it from the leaves while in the same time promoting phosphorus and potassium uptake, and it worked definitely. But then this really depends on temps, humidity and microbial activity which is high in my grows. Then, I'm an outdoor grower and indoor rules hardly apply to what happens with my plants. As far as water is concerned I dropped filtered water as I started seeing what I thought was mild calcium deficiency and replaced it with water from my nearest stream. Can't you just get your water from the nearest river, man?