White algae in tank

The white stuff I get in my fish tank is from the hardness of the water. It's just a mineral build up. To get it off the side of the tank usually requires a razor blade. I haven't always had luck getting it off things that were not glass. A good scrubbing with a sponge may help a bit though.

 

With the locale of it and your hardiness, its most likely the mineral deposits that Chickerdoodle mentioned.

It could also be clouds of good bacteria if the tank is insufficiently cycled.

It could also be other aquarium organisms, like planaria and other wormy things.

 

Planaria worms are usually in the substrate or free floating in the water column and are often due to incredible overfeeding and a build up of organic matter. It doesn't sound like that is the case here.

Even in water that is not hard - the black plastic suction cups will turn white or have a "whitish film" on them. Neither that, nor the white film on your heater is anything to be concerned about.