Pump????

[JByrd]

What size pump would be good for my new 125 gallon tank? How many gal/hr?

[ChemE]

If you plan on direct feeding your skimmer with 100% of the raw overflow water, then 1.5-3.0 tank volumes per hour is your target range. If you plan on doing the more typical and less efficient skimmer is in first sump compartment but is not fed directly from the overflow, you'll want to go up to 3.0-5.0 tank volumes per hour.