Newbie question for DYI wet/dry filter

[mproctor4]

I've been out of the hobby for several years and have recently purchased a 120 gallon tank. Previously I had always used canister filters but have decided to attempt to build my own wet/dry filter for this tank. I'm wondering if a dual over flow box rated at 1200gph and a return pump ca3000 would be large enough?
I am NOT mechanically inclinded and I'm sure I will have additional questions throughout this process. I greatly appreciate your help. BTW--have been browsing this site off and on for a few years now and really enjoy reading all the different opinions. It is a great site.

 

[tank a holic]

you want a return pump rated at less GPH than the overflow

 

[mproctor4]

Thanks for responding! Any idea how big of a pump I should have for a 120gallon tank? What is interesting is that they were selling them together. Nice that they pair them up correctly