you need either another block or hydroton to lift the plants up a little. you only want the roots 25% up the cube to get wet now! by doing this the roots will now start to grow large because their growing downward looking for water/nutes!
Lets see some pics bro, thats the best way to help you!
Once there 6" tall I top them, just pinch of the very top flower going out and walllaa.......4-5 new tops!
KUSH
So here is my simple set up. I have 7 GDP and 3 OG Kush. the two in the back turned a little yellow cuz i had the lamp too close. after i backed it off they started to get the green color back. they are in 6 inch rockwool and i was planing on placing them over some hydroton, and also placing hydroton all around them.? what do you recomend i do with this set up i have? im also under a 600 hps.