[stugiv]

Saltwater? From what I've read, it's a general rule to change raw water cooled risers/elbows every 5 years or so. When I changed mine, I wrote the year on them with a sharpie for my reference or any future owner.

You could use an infrared thermometer to check the temps of the risers/elbows. According to my surveyor, if they're much above 160 degrees, they're probably getting clogged with scale. Prior to changing mine, the highest temp I recorded was 185 while 135-145 seemed to be normal operating temps for the risers/elbows.