Try pro-tekt from dyna gro. I talked to one of there sales reps on the phone awhile back. He recommended it especially for pro-mix growers. Plants grow thicker sturdier stems,increased drought and heat resistance, and helps with stress. He sent me a bottle,and I must say it does wonders. Just a few things thou.....always add any silica additives to your resivorer first. Other wise the silica will bind with any Cal in the Res and will turn it a milky white color. Also,once you start using continue every feeding because silica is non mobile and will not move through the plant once use is stopped