Nowadays technology, power consumption is same for both fresh vs salt pumps. Corrosion and noise are reasons you must consider. I used 2 fresh pumps in the past to circulate 1000K salt water but I would not go that route again. If you care about noises, you might need a few smaller and quiet pumps to move massive water ( and few good MP40/MP60 like to void dead water/good flow in your tank) otherwise, it will vibrate and humming sound like a manufactory in your house. I have both 10K gph and 4.5K gph pumps and they are very very lould for outdoor fresh water pond but they are out in backdoor so I don't care much. AND Fresh water pump use metal ballbearings and might get corroded while Saltwater pumps use ceramic seals.