Thank You folks for your thoughts and insights, they are very helpful. I had previously thought that one day when my existing pump (2hp Max E Glas II - P4EA6G-188L) stops working that I would then replace it with a 2-speed option. This all started because I noticed some pumps available for cheap on our local used market and thought that maybe I could do something in the meantime. I initially thought of the 'in serial' connection because one of the used pump options did not have a strainer basket attached. So I thought that if I put it after the other pump that the 1st pump's basket would strain the input for the 2nd pump. With the restriction issue pointed out, I will be abandoning this idea in lieu of the parallel option if I go the 2 pump route. I'm currently installing a brand new Goldline GL-235 Solar controller that we purchased for this. I have not read where this model can do the High speed, then low speed kickdown. What I have determined is that the 2hp pump does a great job at cleaning the floor but it is entirely overkill when it comes to solar. Unfortunately I don't have extra plumbing into my pool to seperate the cleaning and solar as would be optimal.