Rough plaster solution

[john_in_dallas]

My pool's plaster is nearing end-of-life, and I am not financially prepared for that major work. This past summer my pool was attacked by black algae, a battle that I apparently won by draining the pool and blasting every inch with a pressure washer. Of course, blasting the black algae resulted in some areas of rough plaster. Recently I used "Patch-It" to fill a small defect on the bottom of the pool, and I noticed some rough plaster nearby, so I added a bit more water to the "patch-it" material, to the consistency of thick paint, spread it over the rough plaster area, and allowed it to self level. The next day, the patch looked great, and the rough plaster area was smooth as silk. Here's where I need your expertise: If I fill the pool now, what will happen to the rough plaster area that I smoothed out using "Patch-it"?? Will it fail immediately? Fail after one month? A year?

There is approximately 10 square feet of rough plaster that I would like to smooth. I assume that there is a reason why I have not found a single post anywhere on the internet about this method to repair/smooth rough plaster. Most forums recommend smoothing rough plaster using a circular sander with specific grit sanding pads. I have patched several shallow bad spots/cracks in my pool and spa using "Patch-It" in the past, and they continue to look great after several years. So I am curious how the exact same plaster patching material will handle the "smoothing". Please enlighten me! Thanks!