what does the manufacturer of ur plaster say? i would be following that. since if you divert from it you might hurt in a warranty claim if one should arise.
I have a couple of pics to share with you:
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This is one of our expert's pool plaster. He had them do a warranty repair on this spot. You can see how fast it faded. The pool was less than I year old at this point (I think). This pool has only known the TFP way and had excellent care from the moment it was applied.