Quote Originally Posted by proximo View Post
I collected some of the residue with an ear bulb thingy and placed it in a jar
Good thinking!

Filter sand should be quartz (unless you've got some sort of filter goop in your filter). With a digital macro photo OR under a hand lens, you should be able to see if the sand particles are quartz bits and crystals. Also, if you put bleach in the jar -- if it 'dissolves' or lightens the particles overnight, it's not real sand.

What about the cloudiness that we sometimes see after brushing?
What sort of pool surface do you have? Painted concrete? If so, it's just epoxy chalking (that's how it wears!).