How do I know when to replace my spa cover?

Until recent times the foam cores which make up the rigid internal structure of spa covers and provide the insulation were wrapped in plastic and the joins were taped but not sealed. The problem with this is that over time the steam would condense and form droplets and then slowly saturate the insulating foam cores.We all know water is a poor insulator and once your spa cover becomes water logged it became a great conductor of heat.

"If your spa cover has gained weight like a sumo wrestler since it was new and you struggle to lift it then you can be fairly certain that it is waterlogged and it is time for a new cover."