Right then girls and boys I need some help

I'm planning a 5 foot system which I'd like to use a water fall scrubber in a sump under the tank

What I'm thinking is 1st chamber inlet and scrubber second fuge type place for pods to live/breed 3rd chamber return pump

I'm told the screen size is decided on how much I will be feeding is this correct

As the tank will be new and the rock I have is dry so will need seeding and cycling

How would this affect the scrubber do I run it from day 1 or after the cycle??

Can you let me no what you think im open to any tips or comments so don't worry if it's a crap idea
Let me no
Thanks