Ahhh I know exactly what you mean... When you start directly in 4in cubes this can happen... When I got back into the game after many years of being MIA in the field, I went to using hydroponics from my traditional method of Soil growing... I found out quick that watering to often when they are young like that will cause the slow growth. I recommend next time using the little cubes for seeds after germination, then putting them in the 4in ones when you see the first sign of roots. Also, soak the cubes in a very low dose nutrient solution before doing this(since rockwool is inert). Don't water every day. Rather, give a nice watering till it's soaked but not over saturated, then wait a day or two or more, till it needs more water. The easiest way to tell when it needs a watering is to simply pick it up. It will be like if water is needed... I notice you have a flood table... Don't start using the flood and drain till the plants are big enough (usually when you see the root mass coming out of the 4in cube) to use the nutrient solution effectively... I will also tell you this now since your in the early stages that you might want to through some hydroton clay pellets in that tray because when the roots come out the bottom of those cubes ( and they will) they will be exposed to light Wich could cause alge growth on the roots Wich in turn could steal oxygen away from the root system, which in turn will give you weak stems, and slightly sub par buds. Roots love oxygen. Don't Rob them of it lol I would say, if you are watering them every day, don't. See if that helps with the drooping.
