I'm no expert but it looks like someone poured some chlorine down the side of your pool. I'm amazed however that it could do that though. Maybe it was granular and it sat on the side and bottom for a while and bleached it. I really hope the acid wash works for you, otherwise I would be talking to the PB or service company- whoever is at fault asking if you should contact your CSLB, the BBB or even an attorney if they don't want to help solve the problem together. The contractors should have a bond with the CSLB you might be able to access unless it has been too long. Find out how long you have before the bond liability expires too.

FYI, the stainmaster is not a good idea, long term. The application of acid locally underwater will remove a stain and all will look well. But, over time, that spot you treated has a totally different property than the surrounding area. For lack of a better term, if you know the great spot on Jupiter, you will understand. The pool finish will stain from chemical use over time as a part of normal wear. That spot you stainmastered will stain differently. It stands out like a sore thumb or "great spot" after time. It takes longer, but you will get a nicer job if you immediately lower pH to drastic levels and brush. The precipitate is not leftover plaster, it is a natural curing process that occurs as the plaster is made wet. The lower pH will dissolve that precipitate and prevent it from sticking. You need to keep all equipment off and then bring the pH/alk up with bicarb.

I have this problem on a beadcrete pool and posted a sketch of my thoughts on this issue at the URL below. My pool is inconsistent in excess plaster so I have decided on a regular manual acid wash requiring draining the pool since more acid and more plaster removal can be concentrated on the areas with excess plaster avoiding over etching the other areas. Here is a link that might be useful: No drain acid wash problem

Hi Goldenbeach-- Yeah-- they're pretty much making it up. While this may be an industry practice, it is not the manufacturer's recommended procedure. Check this out. I found similar instructions online for your product, coincidently when I did the search for mine. Again, recommending acid wash and some other very specific instructions during the application process. I will go back and see if I can find that link and post it for you if you don't already have that info. Here's for the product we used: http://www.aquavations.com/docs/CS%20Product%20Data.pdf I previously read this but had to research it again to find the document. I asked the construction manager if they were going to do an acid wash, and was under the impression they were going to do it per manufacturer's recommendation as stated in the document in the above link. I knew I would have to "gently brush" for "about 2 weeks" and was also told I couldn't use the heater during that time. No problem considering we were doing this in mid-September due to many (unnecessary) delays. If I were a violent type (which I definitely am not) I would say something like "I am just about ready to wring someone's neck!" I am approaching the end of the 28 days and the pebble exposure is still less than ideal. But then again, my I can barely type and lifting my arms is painful, particularly my right one after another daily routine of 4 hours + of rigorous brushing! The reason I am making to effort tonight again is because I realize there is very little recourse from the manufacturer if your plaster company is not a "factory trained & authorized" installer. Even if they are there is too much if a chance that your PB or mine won't do anything to make it better as this would involve additional cost on their part--probably the incentive for them not to do it the manufacturer's recommended way the first time around. The product (no matter how good it is itself) is going to suffer from this type of exposure technique IMHO. I was totally caught off-guard on this one thinking I had asked and gotten the answer I needed that it was going to be "acid-washed". I would have never agreed to this alternative procedure due to my age and health condition it has been a real pain in the neck . . . and every other body part --literally!!! I addressed this disappointment with the plaster applicator at about the 2 week mark and was told they might be able to do something about it in the Spring (he would check with his boss). So far, no update on that. I am not holding my breath-- neither am I waiting for anyone to take any action to improve the situation and have just continued to do what I have figured out results in some improvement. Again, E-mail me if you wish to compare notes. I try to do my homework ahead of time and I hate being blind-sided. I feel mislead about the process by the PB and will be letting them know that again I expect on day 29!. The day of the plastering I was told by the sub that he wasn't going to do the full exposure with acid because it would streak the darker blue colored plaster. I don't know if there is any credence to this, but there are no caveats in the manufacturer's instructions. I did notice a change in the color of the plaster anyway as it is curing it is getting darker and often appears grayer. This is not so much of an issue for me but the inability to even get in the sub 60 degree water and trying to get to the bare or under-exposed spots in virtually unreachable locations is killing me (almost literally)!!!