not sure bout ppm as most use ec readings if plants are hungry feed them
raise their in stages each week take it up a notch

only add nutes when ppm drops below half wat u set it at

e.g. if u set 600 ppm wait till it hits 300 then top up nutes


hope this helps

water
water Reviewed by water on . PPM Question So I just got a TDS meter on Friday and I have a question, but here is my info first: My tap water is around 300 ppm. I changed my res for the first time on 9/28 and added 55 ml of nutes. On Friday (10/5), my ppm was around 500 or so, so I added 30 ml more which brought it up to around 700 ppm. Yesterday (Sunday) it was down to a little under 500 ppm, so I added around 50 ml more nutes which brought the PPM to around 875. My reading tells me that 1000 PPM is about average, and 1500 and Rating: 5