There you go. I was going to suggest feeding for 15 minutes on and 45 off. If you say your medium is drying out in 45 minutes; ?that is the perfect time to feed again. So run pumps 15 minutes every hour, when the lights are on. you will always be fine doing this. this is also approx. the way it is done in commercial greenhoues. I don't believe in constant watering, because the rootball does need to breath and your planys will love you for it.