Hello Roger, I was told by someone here (sorry I forgot your name) that the 6000 is easy to upgrade to a 6100 by replacing the transformer. I already read somewhere that this is true. Can you tell me how much I can get a new transformer for? My current pump/transformer is rated at 1850 gph, what is the gph of the upgrade? Also since I'm asking all these questions anyway, can you tell me how to do this? Thanks a lot......oh and could you give me a link or something where I can purchase this transformer. Thank you.