I'm setting up my ebb and flow table i have 7x7x10 inch planter and grow rocks ...the flood table will flood the planters about a third of the way up ...how deep do i put the 3x3 rock wool cubes in ...does the flood water need to touch them or just below...??
Deep enough that the grow rocks cover it, so about an inch below the grow rocks (2-3 rocks high above top of rockwool)
What I'm asking is ....does the 3x3 rw cube need to be completely covered by water when the table is fully flooded ...or just part of the cube submerged in water ...or does it need to be just barely touching the wet flooded grow rocks in the 7.5"x7.5"x10"grow pots on the flood table....also how much extra grow rocks should go in the planter that don't get wet... 1-2 inches...??
No professional here but I'll explain how I feel it should be done anyways. Place a drain down to your res just below the height of your rocks, and about the height of your rockwool. Let the pump fill it up n spill over into that and then when the pump turns off also act as a drain and drain it back out completely.
Flood the whole thing to the top ......the "Flood" is to push out all the gases in the Medium.......and then when the flood recedes the fresh air is pulled in as the water leaves.....if ya' don't flood all the way ya' will get build-up