Gel works, powder is more highly recommended, neither are necessary but do help. I've only tried the AG for cloning once and 4/5 rooted without domes, misting twice a day. I get 99% success just using a humidity dome and rockwool cubes. That said I've put 6 clones in the AG yesterday so we'll see how they go. Used rooting gel, but once it's all gone I'm going to try powder.