How to measure for new Skimmer Cover/Lid

[lardo5150]

My Casa Newport covers, after 4 years from salt, look like poop.
I need to replace them.
Was thinking of buying some plastic ones and painting them, but after reading here, seems the paint will start to peel up.
So may just spend the money on new Casa Newports.

What is the proper way to measure the size I need. I see different sizes...10, 9.9, 9.8, 8.9, etc...

Where should I be measuring?

 

[Rancho Cost-a-Lotta]

Is there a make/model number in the skimmer somewhere. That may be a better way of getting the right size.

 

[Rancho Cost-a-Lotta]

The staining you're seeing may be calcium build up. Have you considered cleaning them up with a mixture of vinegar and water or maybe even a bathroom scale remover. I love the look of those.