I had this problem in a second floor bedroom, in a house built in 1837. I used plaster washers to pull the plaster tight to the lath wherever it was loose, and used the mesh tape and joint compound to smooth over the whole thing. I'm not a pro, but have done a fair amount of taping and repairs over the years. It took me about 5-6 coats to get it all smooth, sanding in between where necessary. I used a sanding block that goes on the end of a vacuum cleaner hose to cut down on dust, but this is a messy job. Once it was painted, you can't even tell a repair was made. I have several other areas in the house to do, and have been procrastinating something terrible. If you don't have the skills and don't have the patience to learn on the job, a drywall/taping contractor or plasterer could do it. Just a thought, I have some bad spots in a stairwell wall that backs up to a tiled shower on the other side. I know the previous tile had bad grout, and suspect that some of the skim coat is letting go because of the moisture.

These are more calcium areas. The pool plaster surface is no longer bonding to the subsurface. The cracks in the plaster are allowing the water to get in between the new plaster and the old subsurface. Do you know how the subsurface was prepped before replastering? Do you know if the pool had been resurfaced once before you had it done? Is the warranty you were given for materials or workmanship?

I wouldn't worry about the delamination at all, this is not abnormal with an older existing pool finish thats due for resurfacing. Your best bet is to toss the pressure washer to the side and grab a hammer. Walk around every square foot of the existng plaster and knock on the door with your hammer. When you hit hollow sounding spots chip the plaster off to the point of where it has good adhesion to the gunite. This has nothing to do with your staining issues. Yes your plumbing was incorrect, but that only led to staining of the pool finish and premature corrosion of the heat echanger, it has zero impact on the adhesion of the plaster to the gunite. Do not replaster over the spots where you hear a hollow sound beneath. My guys tap the plaster on our remodels, if we have good adhesion we use bondcoat, if we don't we chip out the hollow areas, tomahawk the rest of the finish, bondcoat, and replaster. See ya, Kelly

I refurbished our gunite a year ago. I believe it was about $20 a bag at Adcock. There is a light blue that is only a couple of dollars more than the white. Ask the prices. I maybe can get you the name off a remaining bag of plaster. Our pool is also 35,000 and material and labor was less then $2000, because I worked alongside mixing plaster and pouring.