saltwater sump setup any comments

Each chiller defines it's own recommended flow rate. Depending upon the individual chiller (Manufacturer) you could go with a 1/10th or a 1/8th for 79 gallons. Be careful as some chillers keep the temps +/- 1 degree while others are less efficient at temp maint and could be off as much as +/- 3 degrees. This is a big swing for the tank to go through IMO.

You also need to look at are you planning an upgrade soon becuase chillers are no cheap item. If you are lucky you can find one at your local reef club or even check out Craigslist..but you must really check over a used chiller. HTH

It would be way less expensive in both outlay and carbon foot print if you could get by with evaporative cooling instead of a chiller. This also tends to swing the tank temp less too. Something that should be, at least, considered.