asobo-

I would opt for the 2 speed over the 1 speed to realize significant daily savings in energy by filtering at low speed. Low speed operation allows the pump to work easier while still moving enough water to handle filtering and turning the pool water. You don't mention if you have a chlorine generator. If so, this is all the more reason to go with a 2 speed to allow longer on cycles that will provide chlorine needs for your pool also.

Hope this helps!

Yes, your chlorine system is an important consideration. I have an ozonator and it doesn't make ozone unless the pump is on full....meaning I have a 2 speed pump and I can hardly ever use the low speed except in cases where the water is TOO clean or has too much chlorine in it.

what about the electric needs. I had a contractor tell me that since I originally had a single speed I needed an electrician to install a switch for the 2 speed. is that correct?

I have a two speed. My low speed runs for about 6 hours each night and then my high speed runs for about 3 hours in the morning. It's supposed to save me in electricity.

Yes, you will need a new timer (which is a switch) so that you can operate the second speed. I have two timers but someone said they had one timer that did both....I would look for that if I were you. You could do it yourself if you knew some simple home electrics...and where comfortable with wiring a light switch...however be careful because you will probably be working with 220.