pleatco PCC80-PAK4 Replacement Cartridge for Pentair Clean and Clear Plus 320, Pack of 4 Cartridges

They were a perfect fix for my replacements.

I order these once per year, never a problem

Perfect fit.

I should have bought these sooner. Fit perfectly right out of the box. I have to believe those reviewers who said they had some difficulty installing these cartridges must not have ordered the correct part. They fit very snuggly in the manifold, but, isn't that what you want? I was able to push them on with just a small amount of hand pressure in both the manifold on the bottom and the fitting on top. Changing the cartridges took less than 15 minutes.So, why did I replace my cartridges? My pool is only 3 years old, but, I was having a problem with getting my old cartridges completely clean. I would take them out and spend time with the hose on high pressure trying to get into every crevice, put them back in and still show pressure readings in the mid 20s. Within 10 days the pressure was back up to 30psi. I had to clean them monthly in order to keep the water clear (yes, I checked all of the chemical balances and my salt system was working properly with proper salt levels). I even tried some chemical cleaners when cleaning the cartridges thinking that the high pressure water was not enough to get them clean. I have a variable speed pump and when it went into low speed mode my salt system indicated low flow and I was unable to get the pool water really clear.When I put these cartridges in the pressure dropped to 15psi on high speed and I have better flow rate than I have ever had. I was able to cut the low speed on my variable speed pump in half and (at pressure readings of 12psi) I still have sufficient flow rate for the salt system and heater to operate. My pool sweep is running almost as fast on low pump speed as on the higher cleaning cycle speed. Within 4 hours I had sparkling clean water again.I should mention that this is not our first pool. At our previous house I had a Hayward paper cartridge filter in which I had to clean the cartridges once a year and never had the problems I have had with the Pentair filter. Given the choice I would avoid the Pentair filter. In my opinion the Pentair equipment (pumps, filters, salt system) are inferior to the Hayward equipment. Hayward equipment is more expensive, but you get what you pay for.

Update as of July 2014:After about 6 months of using these filters, I am still very pleased. I have taken them out and cleaned them twice, and the filter material is holding up very well. Initially the fit was a bit snug where they mounted onto the housing, but that has loosened up a bit, but not too much. I am considering purchasing another set of filters so I can rotate them and take my time cleaning the filters. This way, I don't have to set aside an hour or so on a weekend to disassemble the filter, clean, and reassemble.Like other reviews have stated, the quality of these filters is very good, and the price is considerably lower then local pool supply stores. The fit was a bit tight, but I used some o-ring lubricant and it helped.The price was actually a bit cheaper to buy these one at a time, instead of the 4 pack, but the 4 pack was being shipped to me with Prime, so it was worth the extra $12 or $15. I get a lot of packages in 1 day with Prime! This was no different.I have been battling a bit of algae in my pool for the past few seasons, resulting in extra chlorine being used and a lot of brushing in the areas that do not get a lot of direct sun. It never occurred to me that just hosing off my old filters could be causing this.... duh. I put these 4 filters in, and within a couple days, I have no algae in the pool!! I wish I would have changed them sooner!! Lesson learned by me the hard way, but maybe it will help someone else out. Don't wait, hosing off the old filters is not enough after a few years.Unrelated to these filters, I stripped out the brass T nut that holds the band on my filter. After being quoted $40 from the local pool store for the nut, or $250 for the whole band, I decided to get creative. I went to the local home improvement store and bought a 4 pack of stainless 5/16 - 24 TPI nuts, and carefully tightened all 4 nuts at the same time with 2 wrenches. It snugged up without issues or leaks. I will replace the correct brass nut, but not for that price, Amazon to the rescue I'm sure....