First Timer Need Some Help

Me and a buddy just made a home made flood and drain setup and its done we just think we ran into some problems.

for one the trays we got when they drain they do not drain all the water out it leaves some water at the bottom maybe a half a quart?.is that gonna drown the plants or will that be ok?

and the other thing is the pumps we bought to pump the water to the trays we think might be to powerfull. they fully fill the trays in 5 minutes and draining takes around 10.We will be using starter cubes at first then move them to the grow cubes.it will take probally one min to reach the correct water level for the starter cubes..

any help would be great,thanks alot

Having a quick fill in many cases is a good thing. It won't matter how fast the system fills up as long as the overflow is big enough to keep the level where you set it.
That's the only real worry with flooding and such!!!
As for water in the bottom of the tray, are your cubes suspended above the tray or resting in the bottom of the tray?
If they are suspended, then it's no big deal at all. If they are in the tray, then the rockwool might stay too wet. Correct that by putting the rockwool into pots and filling the pots with some media like clay pebbles or hydroton in order to put them at the right height.

What he said. Rockwool will stay much too wet if it sits in water. Your plants will rot. Some roots in water all the time can be good however, especially if you have power outages. Expiriment with on/off flooding times. You goal is to have the roots as dry as possible without stressing the plants.

Clay pellets in my opinion are much better than rockwool. Not so many moisture-related problems, and completely reusable.