I just took ownership of this house about 2mo ago and pool was in OK shape, had to redo a few things, ended up converting it to Salt water, fixed the LX400 heater, fixed the Caretaker 99 5way valve, replaced the cracked CL580 filter tank bottom, replaced the seals on the motors, the list goes on.....
During the drain/refill (350+ CYA reading, tested 3x on my K2006), we ended up also acid washing the plaster. There is an area around the Spa side where the rocks have excessive Efflorescence (thats what I think it is, doesnt look like calcium to me, unless Im wrong) build up. Normally Muriatic acid mixed down to 4:1, 3:1, 2:1 (whatever you need) will take care of that and burn it off. Ive done it about 4x on this rock wall and only got it about 25% cleaned, the scale on it seems so thick that its not going to come off that easily or get burned off by MA. Ive even done 100% MA (at 31.45%) on it and it still doesnt help any. Im afraid to take a brush to it as brushing it back and forth with MA is going to sling/fling MA all over the place including me.
Here some pictures of the main trouble spot (will post links instead of embedding them since they are larger resolution, wanted to keep the detail in the pictures). And PS, its wet because I just tried it again by pouring about of MA straight out of the jug to see if it would eat more of it, it didnt seem to make much difference.
This is the overall area, you can see the large white spot near the base of the spa rock wall and the pool stone coping.
http://img836.imageshack.us/img836/8969 ... cence1.jpg
This is a closeup of that large white area, that one rock has I would say a good 1/16" to maybe 1/8" build up on there, some of the gaps between the rocks have even more buildup.
http://img51.imageshack.us/img51/8494/e ... cence2.jpg
This is some other areas on that same wall but not as bad as the one above.
http://img607.imageshack.us/img607/6580 ... cence3.jpg