My saltwater pool was total redone it been about a year and half seeing rusting around pool light and staining new surface. The pool contractor did the chemicals for 2 or 3 months after water was add and my pool service company took over. The water is crystal clear except the rusting around pool light
The contractor is saying it the pool service company fault and they voided the warranty the water is not balanced. The pool service company says no and stands behind their work and have recorders of water numbers I have use this company for years always have done a good job
We have seen pool lights made with different stainless steel housings that have all seen rust – we suspect an issue with the source material used in them. The same has been happening with stainless screws. If possible, have your pool company swap your light out with one with a plastic housing and you shouldn’t have any more issue. You can use ascorbic acid/stain free typically to remove the rust stain.