Traditional Incoloy heating elements on spas over time become coated with calcium deposits that diminish the effectiveness of the heater which also results in costing you more to heat the spa. Having the heating element replace is the solution. But I recommend getting a Titanium Heater that maintain heating efficiency over time, does not easily attract calcium deposits, and last much longer than traditional incoloy heaters. It is strongly recommended to use HT Stain & Scale regularly to help prohibit calcium deposits from attaching to your heating coil.