That's what I would think too but I've read that it is meant to be a supplement to tap water which already has some cal & mag in it so if you're using RO or distilled water you need to add more than the recommended dose.
SmokedSinse12 Reviewed by SmokedSinse12 on . how much calmag plus should I add? I'm using bottled spring water which has a ppm of 50 before I add anything to it. The calmag instructions say to add 1tsp/gallon but I've read on some boards that I should keep adding calmag until my ppm reaches 250-300. Is that correct or do I risk burning my plants? Rating: 5