i made my own aeroponic cloner and had roots in 8 days exact. i would say the manifold should be around 4 inches under the neoprene collars. It shouldnt really matter though as long as its horizontal or lower than the pots. When you run your pump you should have a fine mist spraying in every cubic inch of the reservoir. Just be patient and if your clones dont die then just keep waiting. Also, getting some cloning solution might help not cloning gel or powder but the nutrient solution