Caribbean Blue standard PebbleTec.
A short, 12" crack (non-leaking) had developed on the rolled edge of the spa seat. The cause was a plaster delamination from the gunite substrate. It's a pretty standard type crack that can develop and can happen on any plaster surface if a gap develops between the plaster and gunite during troweling. I honestly wish I did not have the crack repaired as it was not leaking and probably only visible to me. As you can see, the fix was worse than the problem. The patch has faded quite a bit now that it's a year later, but it's still noticeable.
The instructive part of the picture is the color difference between the bulk plaster and the surface. As you can see, the plaster color in the surface region faded to grey. This will happen to ALL plaster. Chlorine, whether at industry standard levels or TFP levels (TFP levels are better), will fade plaster because it bleaches out the plaster colorants. Blue colors are the worst for this because almost all of the dyes used are organic in nature and thus subject to chlorine oxidation. Dark grey colors will usually fade to light grey (and in many cases with a lot of streaking). Only pure white plaster will not fade because...well...it's white.
To answer your question - you'll get about 3-5 years out of the plaster color before it fades.