draining of the h20 in the growing cup
 

hi ron,
i need your advice.
i am using rockwool for my hydropnic system but it seems that the water retention is greater than what i expect. the rockwool i use is not the same of those the market call rockwool cube. this rockwool i use is the same material they use in insulation and looks like cotton. i layer them horizontally to the base of the growing cups. i think this may be one of the reason why the draining of the h20 in the growing cup is really bad. the fiber in the rockwool seems to be blocking the water from dripping away.

will using cocofiber plus perlite solve my problem ?

Yes your medium is acting like a sponge and not letting the water drain enough. A more porous medium will hold more air and drain better.
Ron