how overflow works

[andyc228]

idk how overflow works does it have to flow more gph than the return pump? and also how does it start flowing?

 

[geeimatree]

the flowing down is equal to the return rate because the water going up will push the water into the overflow

it starts flowing by water overflowing into it

 

[andyc228]

so what if i get a pump about 1200 gph , how big a pvc pipe i need to make it