Here are images from a customer who used a No Drain Metal Stain Eliminator Kit on an in-ground fiberglass pool. The pool was completely stained, but the stains were lifted, sequestered, and eliminated with a CuLator Ultra 4.0
What is interesting about this pool is that we noticed that there is no metal touching the water. So, we asked the pool owner if the water was bonded (which equalizes the electrical potential) and he found out that his water was NOT bonded. Once he bonded the water, his metals were not immediately plating out onto the surface.
You not only have ground your pool equipment, you must also bond the water. Yes, these are two different musts. Many new fiberglass pools are not bonded. Please check your pool!
Here is a great site about Pool Water Bonding.