I gotta say i agree with frank and stinky .I used to swear by superthrive although i to still use it in veg i have found that it hinders plants terribly in flower leading to fluffy buds and heavy growth stunt in some strains. Pharma can is right it works great as a ph down if your stuck ,Ive done this my self but wouldnt use it full term. i find that it works best early veg and rooting clones.I also use ro water and was finding it hard ajusting the cal mag from veg to flower but advanced nutrients have come up with sensi cal mag grow and bloom there research proved what i had been assuming that the plant uses differant ratios of cal mag in veg than it does in flower. tell me do any of you adjust cal mag from veg to flower.this product has sorted out a major headache for me.the postman.