This is a resource for spa-owners including a maintenance schedule, trouble-shooting, winterizing steps and water treatment.  

One of the most common reasons a spa cover may be ruined is due to overuse of maintenance chemicals, specifically CHLORINE. Chlorine will release gases which breakdown the foam core and will allow water to saturate the material, sometimes making it VERY heavy. Please be careful in the amount of chlorine/bromine which you use (follow proper dosing recommendations) and your cover will last longer. One thing that can be done is to leave your cover open for an hour or so after adding new chlorine or bromine so that a majority of the gases are able to dissapate without being trapped in your tub. Also, be sure to maintain the vinyl. We have various products which you can use to treat and maintain your spa cover. With proper maintenance a spa cover should last at least 6 or 7 years. SunStar Spa Covers, which we at Penguin order for customers, are widely regarded in the industry as some of the best covers available.

When ordering a new cover for your spa there are certain specifications which you will need to know.
Below you will find information about how to measure the corner radius of your spa cover. This is one of the most, if not the most critical measurement, other than overall dimensions.

Measuring the corner radius for your spa cover: