shouldn't have a problem going to 24/0 and PH looks good. I use to shoot for 5.8 in veg and 6.2 in flower. I know the bulb you are using and if you could find a "Daylight" version of that bulb it would be better, be more like an MH bulb spectrum wise. As for the drip cycle I would think about 30mins +/- every couple hours would be better. As said before RW holds water really well. In fact if you have a extra RW cube soak that sucker and then put it in a bowl or something and check it every so often and you will see what I mean.