20" screen width requires at least 2653lph na pump so round off mo na yun sa 3000lph. tapos 20" x 20" = 400 sq in... ibig sabihin kelangan mo ng 400w na ilaw!
masyadong malaki yun yok! after all, ang size naman ng ats will depend on how much you feed regardless of tank size. 1 cube of frozen food per 12 sq in with 12 w of light. so kung maka sampung cubes ka eh di 10" x 12" lang yun with 120 watts of light.
or kung no choice talaga mag diy ka na lang ng reactor... pwede din yun. mas mura yun kesa sa bumili ka ng bago.