Where will your sump be located? Will your skimmer be in the sump or outside? If space is not a concern...
My equipment room is in the basement.
Sump 48 x 30 x 30. Roughly 180 gallons capacity, filled a about 100 gallons with 80 gallons spare to catch overflow from the tank. I also have a 65 gallon brute can with circulating water that I can "dump" for water changes. The bigger the better for the sump and if you can find a way to discard 10% or more of your water without carrying buckets, you will be a happier reefer.
I chose a reeflo orca skimmer 250. This one cannot be submerged in a sump. You have many options here. This is just one... but... with the upgraded cup this should easily handle my tank even with a big fish load. This one is priced right as well.
The SMALLEST sump you might use would be a standard 55 gallon tank. 4 by 12 by 18. Run this shallow. With an external skimmer, you could have a small refugium, room for filter socks in which you can run carbon, and a pump that would push about 1500 gph into your tank. With four bafflfes for bubble traps, this should give you microbubble free plumbing. You might need check valves for something this small to avoid flooding when your system pump goes off.
Many things to consider!
