I have a 5 plus year old 3600 pondmaster hy drive and I love it. My fish spit out some pebbles from a flower pot a year ago and broke the propeller but I happened to find a replacment propeller on the net and got my 3600 up and running again and that was over a year ago. Its my understanding they have discontinued the 3600. I run mine 365 days a year. I purchased a 2400 has a backup while my 3600 was down but the parts for the 3600 came in so quick I haven't even needed to run the 2400 as of yet. I really like my 3600 for its reliability, performance, longevity, value. I'm sure i'll love my 2400 as much when my 3600 dies for good. I realy like the hy drive pumps

Thanks for the info, Sandyl. Based on your experiences and what I've read elsewhere, I'm going to order the 4800.

Bill