Quick EBB&FLOW question

Just started my first ebb&flow system - its the Botonicare 8 grower. I've been a DWC man myself but I have been wanting to go bigger.

I have all of the plants in their own separate pots, but the roots are starting to grow out of the bottom of the pots and down into the tray that the pots are in. I am worried that the light is going to be hitting the roots due to them growing out of the bottom and become exposed to the light? I am growing in 70% hydroton rocks and about 30% the hydroponic soil that came with the system.

I am also flooding 3 times a day for 15 minutes each. After the draining is over, there is still a few cm's of water left in the tray that the pots are sitting in. Should it be draining 100% of the water?

Thanks guys hope someone can help.

I don't know if you have pictures of your setup, You could put a couple of 4'x4'x1" coco mats down underneath the pots...

Also, you can slightly raise one end of the unit to improve drainage if the drainage hole is on one side.

man my roots grow into my tray and are air manicured gradualy dieing off,but i move my plants around.. if you dont move your plants the tray mats are great, roots grow into them and bigger roots bigger______.if you move your plants dont worry about it and let em grow out..i havent had a prob..there should be a small amount of water in the tray that way if your pump goes those roots have something to drink...
try pushing your feeding schedule up to 5 times a day and then the roots dont have to travel as far to find a drink.and that may help them fill out the container..

so once they grow out and into the tray and are exposed to my 400w HPS they will just gradually die off? Shouldn't really be anything to worry about?

Ill try to get some pictures soon. Thanks guys

yeah.. if you dont scoot em about alot of the roots will live. no worries