What size reservoir or reservoir's would i need for 4 flood tray's?
Should i fill the tray's with hydroton rock's or use net pot's?
what size pump or pump's should i use?
Use square kord pots, 5.5" work perfect...each pot will hold about a half gallon of hydroton. by using the kord pots, you will be able to move each plant with ease if / when needed to.
A 200-250 GPH pump per tray...make sure to use cycle or digital timers for the flood times. The whole flood and drain cycle should take no longer than 15 minutes. Cheap standard timers will not work as most have 15 minute intervals. Unlike the digi's with 1 second - 1 minute intervals.