anyone else notice their water dish gets slimy after a couple of days?

I like the look of the my exo-terra dish , but I noticed that my other ceramic water dish doesn't get slimy after a couple of days like the exo-terra dish does.

When I go to change the water , it feels like its got a slippery film like algae or something. but the ceramic dishes I have still feel squeaky clean when I rinse them out.