If you are running a flood/drain system you should not be flooding the rockwool at all. Flood to about 1/2 inch below the cubes.I have all clones from the cannibis clubs. so a week old from being bought, if that helps any and how long should they be watered for. I would say the smallest is around 2 and a half inches and the biggys are around 6 or so inches.
Im sorry I was stoned when I posted this I have a 4x4 table that is ebb and flow but I am useing it as a drip system. 2 lines to each pot for saftey and I have been running it for about 5 min twice a day. I cant see what the rootsa are doing so I am saking to be safe on the feeding cycle. Thank you fro the helpIf you are running a flood/drain system you should not be flooding the rockwool at all. Flood to about 1/2 inch below the cubes.
Once you have your system setup this way you can water from 3 to 6 times per lights on. The reason to water so many times is that the hydroton wont hold much water and as an added bonus every time the tray drains it brings fresh air to the roots.
The length of time it takes to fill your tray to the overflow is the length of time you should flood for (generally 2-6min).
Hope this helps - good luck!!