Always soak any brand of Rockwool in a conditioning solution or balanced nutrients for one day before first use. By Nature Rockwool is basic (alkaline) and by soaking it, it will shift toward acidic.

All one word, Rockwool can hold more air and water simultaneously than soil.

Rockwool, is the most popular hydroponic medium. Rockwool is made from spun mineral fibers. It can also be cut and formed into many shapes and sizes, providing many diverse growing applications. There are cubes, blocks and slabs. Rockwool is slightly alkaline in nature, so it must be treated with a conditioning solution to lower the pH. After soaking the rockwool in a conditioning solution over night, seeds can be planted directly into the cubes for germination. The conditioner also provides B vitamins and nutrients helpful to the plants initial growth.

Expanded clay pellets are a popular substrate for ebb-and-flow systems. There are a few trade names such as: hydrocorn, and Grorox. The pellets are made from fired clay. It is lightweight, semi-porous material that provides good root aeration. Unlike most substrates, the expanded clay pellets don't need to be replaced between crops. Simply soak the substrate in a mild chlorine bleach solution, then rinse thoroughly.

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