Grodan Growcubes are an ideal hydroponics stonewool substrate for growing many crops. Ideally suited for top irrigation (watering can or drip system), the product also performs well under ebb & flood applications. Use these mini cubes to fill container of your choice. It is recommended that rockwool be conditioned by soaking for eight hours in a pH 5.0-5.5 and then rinsing with pH 7.0 water. Roots love these little baby grodans!