"Why is the eye on the filter for the swimming pool filling up with water? Don't rememeb?

Question

"Why is the eye on the filter for the swimming pool filling up with water? Don't rememeb?

Answer 1

What do you mean eye?

The filter will have a pressure guage,  that tells you when filter is not getting enough flow.

If that has water in it, it is cracked.

If that is the case, water will get into it.

Answer 2

Maybe to tell you when the filter needs changed , It could be a flow meter ,Could be there just to let you know the water is going thru the filter.

Give us a make and model?