How far to I fill the tub with water and nutes?

This is basically what I'm making...

http://www.simple-hydroponic-systems.com/images/image001.jpg

About how far up should I fill it with water?

you want the water to be about a 1/2" below the bottom of your net pots.

runsfromdacops said:

you want the water to be about a 1/2" below the bottom of your net pots.

Click to expand...

How long does it take the roots to reach the water? Say I start off in a rockwool cube surrounded by hydroton. Do I have to water the rockwool until the roots reach the water?