Quote Originally Posted by the image reaper
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:
Hmmm... I'm operating under the premise that it is just the opposite - that you factor the water's ppm out of the equation. The nutrient levels are predicated upon the what is best for the plant during its various stages of life; maximum/ideal nutes for maximum/ideal growth. The stuff in your water is not nutrients - it could be anything. So why count it towards the nutrient value that you want to make available to the plants?

Just to be clear, if my tap water is 200 and my target ppm of nutes is 1,000 - my target ppm for the solution would be 1,200ppm.

It should also be noted that supplements DO NOT count towards your nute ppm. So, if, for example, you want to add calmag+, you would do so AFTER establishing the correct nutrient solution ppm with ONLY your nutrients (G-B-M if using 3-part). It is totally irrelevant what the ppm is after adding the supplements.

I switched from R/O to tap water recently and I'm still adding Calmag+ to my solution. I don't know if I need it or not, but I'm only using 1ml/gal so it's just kinda cheap insurance as far as I'm concerned.

PC :smokin: