If the seedlings have there first set of true leaves take them out and they will be fine under lights.if they have leaves on then this means that the plants have a root sytem.but for cloneing and starting seedlings off propagator/humidity domes can not be beat.spray the leaves for the 1st week then after that just chech to see if the clones have took a hold.you can do this by gently pulling the clone if it shows a little resistance then it has roots starting,i personaly always take double the ammount and take out the front runners.but it is important during the 1st week to spray the inside of the lid of the dome and the leaves,this is the only way it can get at water for the 1st week.i always soak my cubes in water with 1 ml per ltr of water the ph it at 5.0/5.5.use a cloneing gel and make a hole that the new clone can go in i do this on a angle so the root has less disstance to travel it will come through the side of the cube rather than the bottom.but domes are very important in cloneing and getting young seedlings going.