It is easy to use the wrong chlorine product on a fiberglass pool which causes the water to get increasingly acidic, dissolving the top film of concrete surfaces.
Technically you need to use a mild soda ash wash to neutralize the surface if acid is still present.
You would then brush on our waterproofing patch material, texture with a towel or newspaper.
Acrylic stains are used for color accents.
This is all included in our Touch-up Kit and we can provide extra patch material so you can apply about 1/2 inch.
You should get many years of service from the waterfall if the pool water is properly maintained.