Dumb Q: Does it sound like my DE Filter has a tear or break?

[edwjmcgrath]

I finally got my pool clear this year and when I added some Cyanuric Acid to the skimmer today, it came out into the pool through the returns.
I don't see how this can happen with a functioning filter.
Am I missing something or do I need to tear my filter apart?
Thanks.

 

[JasonLion]

Welcome to TFP!

There are two possibilities, either the filter is broken and is letting the CYA through, or the main valve is broken and it is letting the CYA through without it ever going to the filter.

What kind of filter do you have?

 

[edwjmcgrath]

It's a hayward pro-grid.

How would I test to determine which it is (short of taking the filter element out and looking at it)?

 

[JasonLion]

When there is a problem with the main valve there will usually be water leaking out of the backwash port even when the valve is in filter position. That isn't true 100% of the time, but it is a fairly reliable indicator.

Other than that, you need to open up one of them or the other and do a visual inspection.