What kind of system? Got pictures? What kind of plug? The rapid rooter types can touch the water, but you might let the water go down a bit from there as the roots develop. In my mind I have pictured seedlings whose roots have yet to reach the outside of the plug. It would be much like the floating plug rafts for the rapid rooters. You transplant once the roots are outside the plug. Of course, if you are using rockwool plugs, I'd say no. They get too soggy and you are more likely to lose plants to damping off.

Do you have all these in the same system?

You can change the light condition of your seedlings once you see true leaves coming, the change in light conditions will depend on the light requirement of the plant youÂre growing, although you can change the light supply of your seedlings to 18 hours as soon as they enter the vegetative stage.