Any Water Gardeners out There?

Jack and I have a water feature in our back yard that has a fairly large pond. Because the pond end of the water feature gets a fair amount of sun and we don't have a lot of water plants, we usually develop an algae problem before the end of the summer. A couple years ago, we discovered that a few water hyacinths (the floating kind) will multiply rapidly and do a good job of shading the pond, which discourages algae growth. They are attractive little plants with a nice bloom and grow with no care at all. 

But, as sometimes happens in gardening (and the rest of life), the very thing that one thinks is desirable can become a nuisance. I love the fact that you can buy a few of these and in two weeks, your pond is nicely covered. But from that point on, watch out! If you want a concrete example of exponential multiplication this is it. You can almost stand by the side of the pond and see them dividing! (Well, that might be a little exaggerated but not much!)  By early summer, these carefree plants require regular maintenance: Jack scoops out dozens of them nearly every week when he takes out the trash.

When Jack and I first moved into our house, this pond had a variety of plants in it that had taken over the pond. Roots had escaped everywhere so we pulled them all out and cleaned out the pond. Now these annual water hyacinths (and a struggling water lily) are the only thing we have in our pond each year. 

Next year, I'd like to have a greater variety of plants and I was hoping you water gardeners out there might have some suggestions. Here are my criteria. The plants must be

1. Winter hardy
2. Reasonably easy to care for 
3. Well-behaved (i.e., not produce a lot of pump-clogging roots)
4. Not from the floral department at Hobby Lobby or Michael's. 

Any ideas are appreciated.