Just to throw in my 2 cents: 3 best things I ever got for my hydro --a good PH/TDS meter, using R/0 water (we have a well) and a good quality light. Cost money? Yep. Worth every penny? You bet they are. Skipping stuff is fine until something goes wrong. And since I'm putting the work and time into them I might as well get a really good yield rather than an average one.