Simply Koi and More Koi

Been a little preoccupied with other things than koi in the last couple of years but Im starting to get the bug again. I need a new pump but want to get one more economical than the one I had. Ive got an Aquadyne 2.2b so need something quite high pressure for the back washing in the summer months but I want to turn it right down for the winter. Any suggestions?
Cheers, Matt