No floating algae in my watering troughs, but over the course of the Summer they get about 1/2" thick buildup of a reddish-brown colored algae on the bottom and sides - doesn't matter whether the trough has pond or well water (or even which well). That stuff is not a problem for the cattle.

"Live like you'll die tomorrow, but manage your grass like you'll live forever."
-S. M. Stirling
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