Yup, I'd go with one (rw) or the other (hydroton), but not both. I can't imagine a need for it. Btw, when I'm using rockwool I use 6" cubes and water them 4 times a day, at 6am and pm and 12 am and pm. Right now I have Royal Gold brand Basement Mix, a coco based soilless mix, in 2 gallon pots that are flooded once a day. That is to say, the lower 3-4 inches are flooded. I'm about to set some timers to flood them 3 times a day, and see if it's too much, but I don't anticipate that.