Janie, I'm not surprised that the manufacturer was surprised to hear about your problem. It's pretty unusual, I would think.(posted 9672 days ago)I'm not clear as to whether the algae is growing in the pump, or if there is just a lot of it getting sucked into the drive pipe inlet. I would imagine that it's the latter; if so, you might want to put a coarse screened filter on the end of the intake. It should be fairly large, so it doesn't clog up too fast.
As to freezing, my climate is pretty mild, and a ram would never freeze, as long as it was pumping. If it was idle, and filled with water, it would certainly freeze, though.
How big a ram is it (like, what is the drive pipe diameter?)