Iv been using half of the recommended dose, Fox Farms Veg nutrients. They reccomend 2 tsp per gallon but iv been using 1 tsp per gallon.
Also iv just recently added a little ammount of cal-mag to help with some of the difficiencies i think iv been having. Iv been using purified water and iv been told that this type of water lacks certain minerals/nitrogen.
It lacks everything, including the beneficial stuff. It also lacks anything that would help buffer it's alkalinity. This means that your water might be 6.0 pH coming out of the tap at the water store, and be in the 7 range just sitting in the bucket the next day. My tap water may be relatively contaminated, but it sure buffers well. It comes out of the faucet at about 7.2 pH, takes quite a bit of pH-down to get it to 5.6 (making it really hard to overcorrect), and then it tends to stay there. It's been a lot of years since I took a university chemistry course but there was a time when I would have been able to explain all of this.
I'm re-visiting the arguments against using tap water for my own grows. The main issues are chlorine and chloramine, right? And the high PPM in the base water make for some added confusion when deciding what the finished feeding should be.