Hydrofarm System

[hydro65]

Does anybody have the Hydrofarm system and can help me out. This is my first time with hydroponics, and I NEED help. How long do I keep the tray flooded. I figure I would do two cycles to begin with, but how long does the tray stay flooded before I have the pump shut off and drain. The instructions do not say. Maybe this question applies to all ebb systems. Also, the instructions said to change the solution once a month, is that good enough.

Please help ASAP!

Phil