The listed suggested ppm levels on your bottle of Dyna Grow is assuming that your water is at 0 ppm to begin with. if you start off at 260 ppm with your tap water and the Dyna Grow says to use 400 ppm, then you must add 400 ppm of your nutrients so your level would be 660.

I would suggest you try to use distilled water, or reverse osmosis water which will have 0 ppm. Your 260 ppm tap water is probably ok, but may contain chlorine or calcium, or sodium or something else harmful to your plants. If you must use tap water, they sell hydroponic nutrients that are meant to be used with tap water and ppm levels around that 260. Flora series by General Hydroponics sells a "hard water" version of their 3-part nutrient line which is meant for tap water.

give it a shot with your dyna grow, just keep close watch on your pH level, keep it around 5.8, change your reservoir every 7-10 days topping with fresh water every day. Good luck!!!!!!!!
Stormcooker Reviewed by Stormcooker on . Got a few ppm questions. Can anyone help? 1. Does anyone know of a link or the stats them selves for what concentration (ppm) of nutes that are best for plants at different ages or heights? 2. When you are trying to get the concentration of nuts in the res. to a certain level (say 400ppm), do you want the water to be at 400pmm of total particles or 400ppm of nutrient particles then whatever the epsom salts will add and what the water started at to begin? Rating: 5