flood level and rockwool

[Illusion]

Is it recommended that the flood level touches the bottom of the rockwool (1" cube inside hydroton) each time I flood? throughout the entire grow.

Also, how do I test the runoff PH? not the reservoir. Ebb and Flow system

[Opie Yutts]

No, have it cover some of the clay pellets, but not the RW.

You test runoff PH with a PH pen. Probably not sure what you mean here.