Yeah, that's what I was going with, despite what that site said.
I do still need it for the Pothos though, I'm pretty sure.

Anyway, I did take the light off for a couple hours to see what kind of difference it made, and it was negligible. It may have changed 1 degree on the land side, and none at all in the water. It seems pretty clear that it's not contributing to the heat, and if it is, it's only minor.
Anyway, I guess it's not really a problem after all, as long as it doesn't get too far above 80 degrees for too long.