Hi, Yes, I would empty the whole thing this year. We have to do that every spring (or most springs, to tell the truth). It's a big job, and we try to sort of schedule an entire day or two for it! We pump the water out, catch all the fish and transfer them to a wading pool-- that we filled a day earlier, so the temps match, use a shop vac on the bottom & shelves, and then usually powerwash the whole thing. That's when I repot the lilies, etc. too if they need it. Then fill it back up with fresh water, dump in enzymes and algae chemicals, and around here adjust the ph down. Have to wait till the next day to put the fish back in, but they seem to love it. Your pump would probably benefit from a cleaning at least once a month or oftener (we usually have dead frogs stuck to it), and if you don't have a good filter between the pump & fountain, you might want to look into that-- it'll help keep the pond cleaner a lot longer (although you will have to clean out the filter fairly often).
I know a lot of experts tell you to never empty the pond, and let it "adjust" naturally, but ours never gets to that point!
Hope this helps.
