So my ppm is pretty high with the city water with the nuts I use puts me over 800ppm. So I was thinking of purchasing a water filter to cut down on the distilled water cost. But what about rain water? I haven't tested it but I would think it's ppm would be low and maybe there is some other benefits. What is everyone's thoughtful. My first thought is " Idon't want to bring anything from outside into my grow tent"