I'm considering getting an inflatable hot tub, however I'm concerned about its ability to stay hot in the winter. Also, I live in Boulder, so another consideration is that I'm at higher than a mile above sea level.

I'm thinking about solving this problem by getting a second electrical heating element, and connecting it in series with the heater and pump supplied with the inflatable hot tub.

would this make any kind of noticeable difference? would there be problems with the pump having enough pressure to draw water through the extra heater?

Thanks.