If I may chime in here with a question as well. I am about to purchase a 2-speed Pentair Dynamo to lower our electric bill. We have an 18" SD40 sand filter (with zeolite) and 1.5" piping (actually, it's still the tubing right now - until we hard-plumb it). We're currently running a 1hp Pentair Dynamo and really like the Dynamo.
Our situation is that, in addition to wanting a 2-speed pump, we will be adding a 2nd return in the shallow end to help with circulation. So would the Pentair 2-speed work for us? From what I've researched already, it looks like it would. BBBUUUUTTTT, my niece tells me that her store sells a 1.5 hp, 115 v., Pentair Dynamo 3-speed! I can't find one online and she hasn't called me back yet today.
If she was mistaken about the 3-speed, this post will be moot. However, if there is such a Dynamo, will that work for our pool as well, or should we just stick with having her order us a Pentair Dynamo 2-speed? Her 1.5 hp could well be an uprated model - don't know, since I can't find it online (while waiting on her to call me back). If she DOES sell a 3-speed, I'm thinking that the middle speed would be better for us, if we're going to add a 2nd return line, which, in my understanding, will add to the resistance flow.
Any info would be appreciated! Thanks.