I've being having an on-going nutrient burn problem during flower and have recently purchased a TDS meter, here's what I found
my tap water PPM = 310 pH = 7.5
adding bloom nutrient @ 3ml/ltr PPM = 554 pH = 7.0
adding bud booster @ 2ml/ltr PPM = 720 pH = 6.5
My next step is dolomite lime my be...