Hello
I picked up cal magic and it says to put 1 teaspoon per gallon but the ppm for that rate are near 500. Should I be doing a lower rate? I’m using reverse osmosis water, so I’m just trying to add some Cal mag back into it. What rate should I be using?
I shoot for 150 ppm cal mag in my nute mix.
Does that reading include your water source? I’ve never seen that amount read 500 PPMs in RO or distilled water 
1 ml of cal magic (Cal mag) added to a gallon of water is only about 40 to 45 ppms. I don’t find it necessary to ever use more than 3 ml per gallon (5 ml max)
Also, you’ll notice that a teaspoon from your kitchen utensil box is different than a teaspoon in true measurements. A true teaspoon is 5 ml
I did a test a while back so i could get a base line of how much all my additives raise EC per gallon. I use cali magic and my blue lab trenchon stick constantly says .2 EC per gal. So basically on the 700 scale thats 140ppm and on 500 scale thats 100ppm. Maybe with a digital readout the ppm might differ slightly but thats what I’ve found. As @OGIncognito added you should see what your ppm of your water is without adding anything first. Hope that helps grow bro
I would verify what scale your tds reader is on. If it’s 700 scale that’s around 360ppm on 500 scale