Thanks deleafer. I started off using Rapid Rooters and a digital irrigation timer from home dePOT w/ a battery backup (about $20). Works great until they are ready to work on just bubbles. Or just any timer that will let you set in 15 min intervals. I also add a bubblepad for precation to make sure the pump is drawing freshly oxgenated water from inside the resevoir and directly on to the Rapid Rooters.