snowflake crystals?

[absolut]

I have a 10 gal aquarium that has two curly q anemones and one maroon clownfish and it has been set up for a while now. I had a brown algae problem at first, but after I got snails that went away.
Now I have noticed snowflake like crystals forming on the walls of my tank and they grow fairly quickly after cleaning them off.

Does anyone know what these are? Is it algae or anytrhing detrimental to the tank?
Thanks.

[Just Fishing]

Are you supplementing and testing Ca and Alk? The reason I ask is that it sound like Ca precipitation. Post a picture if you can.