Cleaned my cartridge filter for the first time and pressure didn't drop afterwards

[bertschb]

We just purchased a house with a pool that was built last summer. I decided to clean the cartridge filter since it most likely hadn't been cleaned since the pool was built. The 600sf Sta-Rite S8M600 filter is large for the size of the pool. In fact, the largest System 3 filter Pentair shows on their website is 500sf so I'm not even sure if the 600sf model is still available. Because of the size of the filter and the fact that my pool has a MultiCyclone pre-filter, I didn't expect the filter to be very dirty and compared to some I've seen on YouTube, it wasn't. But, I still washed out a bunch of dirt.

My filter pressure was about 17psi at a pump speed of 2,800rpm prior to cleaning the filter and it was the same afterwards. IIRC, pressure was 3-4psi at 1,500rpm (before and after cleaning).

Just curious - has anybody else cleaned a filter and not seen the pressure drop?

 

[Jimrahbe]

Brian,

The larger the filter the dirtier it needs to be before it will have any real effect on the filter pressure.

I only clean my filter twice a year and I don't see but a lb. or two difference between my before and after pressure readings.

Do you get anything out of your pre-filter?

Thanks,

Jim R.

 

[bertschb]

Do you get anything out of your pre-filter?

Hi Jim

Yes. I cleaned the MultiCyclone when we bought the house five weeks ago and again today. I flushed about a cup of sand/dirt each time. Based on what I saw today, I'll check the filter again in six months but probably won't clean it again for a year.

Based on what I've read here on the forum I was expecting a 5-10psi drop after cleaning.

 

[Turbo1Ton]

I haven't checked mine since late October. I had previously cleaned my filters last spring. When I checked in October, my pressure had not gone up at all from the clean pressure. So I decided to let it ride, and see what it is this March. If I can get away with only cleaning once a year, I will gladly do that.

--Jeff

 

[Newdude]

Based on what I've read here on the forum I was expecting a 5-10psi drop after cleaning

Most of the people needing a cleaning inherited a pool after moving or hadn't deep cleaned their filter in ages if ever when they learned they needed to. So they all saw a big drop.

The others knew what they were doing and let it ride until it was time, also seeing a drop.

For reference I had a 35k pool with 500s and could go all season, even with crazy pollen. I cleaned them in the spring when the crud was done falling for my own piece of mind but it was just for me. Your 600s with 2/3s less pool and presumably less pollen could probably go YEARS. In theory a moderately dirty filter will clean even better as the crud filters even finer other crud.

Some people hate it but I'm a tinkerer and enjoyed playing with the hose for an hour.

 

[Turbo1Ton]

In theory a moderately dirty filter will clean even better as the crud filters even finer other crud.

Not just theory. In a former life I worked for a company that built hydraulic filter test stands, and even some air filter test stands. Filtration efficiency most definitely increases with debris accumulation on/in the media.

Most lube oil filters we tested started out at around 30-40% efficiency, and by the end of the test, they were >90%. The best ones we tested finished around 98%-99%. Filtration efficiency claims are made based on a dirty element. If your car oil filter manufacturer claims 98% efficient, that is 98% efficient at nearly its end of life. If you maintain your vehicle well, you likely never get to that level of efficiency because you are changing the filter before you get there.

--Jeff

 

[Newdude]

Not just theory.

Oh yeah !! I was just being careful with my words to not confuse any future readers that they could let it fly forever with unlimited efficiency gains.

 

[bertschb]

Thanks for the feedback guys! I'll monitor my filter pressure for changes but I'm going to plan on cleaning the filter once a year from now on. With my small pool, large filter and pre-filter, that should be plenty often.

 

[Darin]

When operating a baghouse (air control device for dust) you intentenially start new bags in manual without purge just to build up a "coating of dust" on the filters to improve cleaning efficiency. Then after a pressure differential is observed we switch mode into automatic purge. Yes a coated filter does work better than a completely new one. So agree not a theory.