I use waterfarms to. The one thing you have to remember is that ring is big.
At first you will want to hand water them because the rings dont get close enough.
just get all around the base of the plant or around the rockwool, not the cube, get the hydroton wet all around it. Getting something to cover the rockwool will help keep it dry, well moist not soaked and it will prevent alge.
I water for one hour in the morning and one hour at night. I tried a third mid day but it was too much. So I would say two hours a day, you can split it up as you like.
Good Luck