Quote Originally Posted by Illusion
Something I haven't been able to figure out is...

Lets say PPM of tap water is 200, vs RO water which could be 50...

if wanted my PPM to be 400 for my reservoir, and Im using tap water with a base of 200 already, Then I would only be able to put as much nutrients in to make it 400, right? But if i was using water if a base of 50 PPM, then I would have 150 extra PPM of nutrients?

So does it slow down growth by using water with a high base PPM since you can't add as much nutrients? or does it really not matter...
I'm just beginning with hydro myself, and you are asking the same questions I was asking an expert, yesterday ... yes, you are correct on calculating the ppm limit ... whatever is left after your water ppm, is the amount of nutrients you would be able to add... and, if you cant add much nutrient, growth will slow ... plus, the high ppm could be because of bad contaminants ... RO water is very low, mine is 004 ... but, with RO, you also have to add Cal-Mag Plus, and I assume that will add to the ppm, as well ... but, remember I'm very new at this, I haven't even set up my equipment yet, still researching ... :smokin: