The mottling on your finish is considered normal-to a point. ALL plaster finishes will have a color variation especially darker finishes which require pigments to produce their color.

First, and I know you said you have been chemically balancing the pool, test for and maintain your pH at 7.2-7.6 ppm, total alkalinity, my suggestion because of salt content, at 100 ppm, calcium hardness at a minimum of 250 ppm 400 max.

SWG's will slowly increase your pH and alkalinity levels and must be maintained to prevent scale. Adding acid might be weekly to maintain those levels. When adding acid, always dilute in a bucket with the pool water in small doses. Adding acid directly to the pool can etch and discolor the finish. The acid is heavier than the water and will go straight to the bottom or sides of the pool.

A sequestering agent to keep the scale in check on salt pools is recommended-Jack's Magic Purple Stuff-on a weekly basis.

The lighter shades made be some calcium coming through from the original plaster. Plaster contractors will add calcium flake to increase setting time. Sometimes too much is added (3% max) and it will bleed through the finish.

Jack's Magic-http://jacksmagic.com/ has some products to possibly remove discoloration and also Easy Care Products-http://www.easycarewater.com/

A light acid wash can sometimes bring the plaster back but it can also etch the surface if not done properly.

Mystic Pools - Thank you so much! I really tried to brush it as much as I can today and was just getting upset, there are small brownish dots that are rough to the touch that seem to be appearing all over steps that will not brush off..seems imbedded. Also noticed our grey tile grout is starting crumble under travertine coping. I’ll probably have to start another thread about that. For a brand new pool, it’s not looking like one. Under warranty but am not sure what to consider a warranty call. Again thanks for your reply.

Any trees above creating this stain? Caterpillars from trees above have caused stains like this.

Or, perhaps an iron stain. In that case, check iron content and add sequestering agents as needed.

Tile grout crumbling can be a host of reasons.

No trees, we are in Arizona. Its pretty plant free. However we do get plant pollen now and again from heavy winds and neighboring hedges. Nothing major. I ordered the purple stuff just now. Hoping this helps.. on to diagnosing tile grout issues. Thanks again!

OK. Jack's Magic has a stain identifying kit which may be helpful.