Overflow question

[crustymonk]

Hello,
I have an 80 DT and have just completed my 29 gal sump tank. I am going to put in a 1200 gph overflow box and was wondering a few things...
1- is 1200 gph to much?
2- If I use a 820 gph pump for the return, will the overflow box compensate for that or do I need need a 1200 gph pump?
3- I have a chiller, can I have the returm pump go to the chiller then the DT?
Sorry for all this but extremely new to saltwater...

 

[burpuffer]

with the return pump you have to compensate for the lenght in return line. i have a 100 gallon tank with a 1200 gph overflow box and with 4 1/2 feet on return line my return pumps about 1150 gph and that works fine.the return pump should be a little bit less than the overflows gph