when I grew with Hydroton pebbles, in large buckets, I had the DRIP system cut on for 15 minutes, anywhere from 'every 2 hours', or longer ... if memory serves me right, I settled on 15 minutes, 'every 4 hours' ... Hydroton holds a lot of water, doesn't drain off as fast as you'd think ... and, you're flooding with a lot more solution, than I did, with just a drip-ring, you should be fine ... keep your reservoir aerated well, too ... :jointsmile: