Greetings all, I am new to the forum.  I just purchased a house with an indoor saltwater pool(12,000 gallons), built in approximately 2007.   It has a water feature (waterfall), and is heated.  I am considering my options for improving my energy consumption as it relates to the pump.  

It's currently a Northstar SP4015X20NS with a Century 1.5HP Uprated (SP=1.47) motor.   I estimate the flow rate to be in the 80-85gpm range which is great for those occasions when I run the waterfall, but overkill when I don't. Given an 8hr rating for turning over 12,000 gallons we get 25gpm, but I also have a 400KBtu heater that has a minimum flow rating requirement of 40gpm, and the salt cell only needs 11gpm.  

My research suggests that you don't offer a Variable Speed motor for the older Northstar SP4000X series pumps.  Any recommendations?

Also can a variable speed pump be linked to a heater to adjust flow accordingly?

Thanks for any replies.