Strange discoloration around the autofill eyeball

[voidpointer]

I have an autofill for my pool. The water comes out of an eyeball to get into the pool. Since summer, I've noticed a brown/red stain around that eyeball, which has affected the plaster around it a little bit as well. I haven't noticed it getting worse. Does anyone know what the cause is? Is this something I need to be concerned about? Picture below.

 

[mknauss]

Likely is iron. The fill water is hitting the chlorinated pool water. Try some crushed up Vitamin C tablets. Place them in a thin sock. Hold it on the stain.

 

[voidpointer]

What does the vitamin C do with iron?

Is there anything I should/could do to prevent staining in the future?

Thank you for your help.

 

[mknauss]

Vitamin C is ascorbic acid. It removes the iron stain and puts the iron in the water. It is soluble and unlikely to be of further issue in your pool conditions.

Nothing you can do. Just remove it when you can see it. Exchange as much water as you can with rain water when you get rain.