Since you've provided nothing for us to gauge off of, and it's apparent that you haven't started your research, I'll say 4x4' with 1000W HID and you'll get about a pound.
Aside from that, how about you share the following with us:
- The size of space your tent will be in
- Temperature and Humidity of that space
- Exhaust fan/filter you'll be using, and where are you venting to/from
- How much liquid space in each pot, and what is the accumulative volume of liquid overall in the RDWC
- Lights you'll be using
There's a lot more to think about than just asking a single question. Start at
https://growweedeasy.com
Consider what you want to grow, do some research, then ask questions.