How to know when to replace filter cartridge?

[tj__r]

We've got a Jacuzzi Sherlock 160 cartridge filter. Filter body manufacture date is 2005, and it's got an aftermarket cartridge in it now, so it's maybe around 4 years old at a best guess. Cleaned cartridge when closing; it runs about 20PSI with filter gauge about 5' below pool water line. Previous owner said that's about what it usually runs, he cleaned when it got up to around 25PSI. Ran whole last summer and it didn't get up to 25PSI. Pool water is not particularly clear, always looked a tiny bit cloudy.

I kinda get that cartridges need replacement when they get so gunked up that cleaning them doesn't reduce filter pressure adequately, but do they also eventually fail by letting too many tiny particles thru? I've inspected for tears or holes, and gaskets still seem reasonably good.

Thanks as always for any advice!

 

[Bama Rambler]

I suppose it could fail by having small openings and allowing debris through the media but that's not normal. Most of the time they fail by either becoming calcified or by tears in the media. If it was micro tears I'd think you'd see the clean pressure go down a little and then not rise as fast when the filter becomes clogged.

 

[tj__r]

Thanks, that's kinda what I thought - that if there are holes, then operating pressure would be quite a bit lower than normal.

 

[mas985]

It would be very difficult to detect a tear in the media. For most cartridge filters, the clean filter pressure is not much different than the pressure without the cartridge media so detecting a tear in the media is not all that easy to do with just pressure. The best thing to do is a detailed inspection at the time of cleaning. Also, if you start to see debris come out of the returns, then you know the filter is starting to fail.