skimmer boxes are high failure points for freezing in the winter since the plastic gets brittle from the cold.
If cracks happen, repairs are costly and they have to break the concrete around the skimmer to install a new one. Epoxy can also be used for small crack repairs.
How to winterize:
1. Use cyclone to blow out skimmer plumbing and use a gizzmo to seal. Use larger size gizmo for inground pools with deep skimmer boxes. Most above ground pools have shallower skimmer boxes and u can purchase the small gizmo. The gizmo should reach as high as possible in your skimmer boxes while still allowing the lid to close
2. Empty all water using: shop vac, Milwaukee transfer pump, sponge/rag
3. Place pool noodle inside
4. RV antifreeze