I have been wondering about this problem for a while now.

Under the spa spill over I have a white crusty stuff build up. Its on both sides of, and under, where the water spills over the spa ledge and runs from the upper spa height to water level. I tried cleaning with diluted muriatic acid thinking it was calcium build up but it didn't come off nicely. I saw some fizzing but not a lot.

That leave salt build up. Is it possible or normal to have salt build up on a SWG pool?
I know the salt levels are normal range (3000-3500 ppm) as my intelliChlor unit reports the salt levels.