Ebb & flow question

I just set up my first homemade ebb & flow system. I've germinated seeds in 1" rockwool cubes & tset them in a 7"deep tray filled with hydroton. when setting up my drain fitting should I set it to fill to 1/2" shy of the top of the hydroton or insert an extra fitting so the water level completely drenches everything? By using the extra fitting it actually caused the entire tray of hydroton to float up about 1/2" & then resettle when the tray drains.

Also how frequently should I flood the tray during an 18 hour cycle & during a 12 hour cycle?

Thanks for all your help.

here's a couple pictures with the drain fitting set at the higher setting.

oops had trouble with images, trying that again.

you dont want the hydroton to float because it will disturb the roots forming and growing below so you just want to flood until everything is wet,

Thanks HL, I'll take one of the spacers out of my drain fitting.

How many times a day should I flood the tray? Right now I have it set to flood for 15 minutes each time (it takes less than 5 min to fill the tray) Starting one hour before the lights come on & then once every 3 hours until just before lights out.

we are doing the same project...this is my girl's journal check it out...we are at about the same point...adding the rocks today..*Smooth Criminal* My Journal
and this is my journal...the soil and hydro grow is on there too..Cali's Kush Journal..20 Clones/1000 Watts.

I would bury the rockwool cubes so that they are just below the surface of the rocks. Then flood to the lower part of the cube, so the rockwool gets wet, and the surface rocks don't.

Flood the first time 1 hour after lights on, and last time 2 hours before lights off. The number of floodings between those depends on the temp/humidity, and how big the plants are. No flood at night. Flood the plants to max level and then drain, no need to soak.

HTH