PSI levels and when to clean your cartridge filtering system

[tstex]

Hello to All,

Have a Hayward C3040 4 cartridge filtering system and I was trying to discern "the rule" of when you clean your cartridges, then at start-up and then when the VSP cycles to normal operating speed, the PSI relationships regarding when to clean the filtering system again? Hope this makes sense.

I will write it down this time.

Thank you very much,
tstex

 

[bdavis466]

25% over the clean filter pressure reading with both readings at the same pump speed and with the same valves open/closed (to eliminate any variables).

Pool Filter Cleaning

 

[tstex]

Thank you Brian...I went to your link and copied it into my Pool Folder File - Regards, tstex

 

[bdavis466]

 

[setsailsoon]

Hello to All,

Have a Hayward C3040 4 cartridge filtering system and I was trying to discern "the rule" of when you clean your cartridges, then at start-up and then when the VSP cycles to normal operating speed, the PSI relationships regarding when to clean the filtering system again? Hope this makes sense.

I will write it down this time.

Thank you very much,
tstex

Unicel (manufacturer of a LOT of filters) indicates 8 psi above clean reading... this seems a little high to me.

Chris

 

[duraleigh]

Unicel (manufacturer of a LOT of filters) indicates 8 psi above clean reading... this seems a little high to me.

Chris

It is too high. mas985 did some calcs for the forum and determined that any time you get much above 25% over clean psi, the pump loses a lot of it's efficiency.

So, it's not that it is dangerous to let your pump exceed the 25%, it's that it is costing you more money than it's worth.

Therefore, you can see that if your normal psi is 10, the effectiveness starts to diminish around 12 -13 psi and gets pretty horrible if you let it go to 18 psi......again, no harm to the pump but harm to your pocketbook.

 

[setsailsoon]

Dave,

I'm glad to hear an expert like you agrees. I just don't understand why major suppliers to the market would make this recommendation. Pleatco and Unicel post the same information even though they seem to have different media manufacturers. Both are a woven polyester fiber with slightly different lobes and both recommend cleaning at 8 psi over base pressure. I think I'll send them each a question to find out the basis of their recommendations and post the responses. Sounds to me that they could be more focused on extended filter life than optimal filtering and pump costs. I did a little test by blocking in the pump slowly to increase pressure and I had to close the valve almost 1/3 to accomplish that. When I look at the pump curve I also see very high operating cost as you point out plus greatly reduced flow rate... but with both manufacturers recommending this I think I must be missing something.

I'll keep you posted on their response.

Chris

 

[setsailsoon]

It is too high. mas985 did some calcs for the forum and determined that any time you get much above 25% over clean psi, the pump loses a lot of it's efficiency.

So, it's not that it is dangerous to let your pump exceed the 25%, it's that it is costing you more money than it's worth.

Therefore, you can see that if your normal psi is 10, the effectiveness starts to diminish around 12 -13 psi and gets pretty horrible if you let it go to 18 psi......again, no harm to the pump but harm to your pocketbook.

Dave,

I actually got a reply from Unicel. Here's their response:

"The basis for our recommendation for cleaning a cartridge at an 8 psi increase was derived many years ago through extensive lab and field testing to determine on average at what tank pressure increase from the initial starting pressure with a new filter element a filter cartridge should be cleaned at to prevent damage to the cartridge as well as keep proper circulation of the pool water. Please note I used the word “average” as no two pools are the same and many factors can lead to a filter element needing to be cleaned at lower pressure increases."


So it looks like the basis is indeed to avoid mechanical damage. I asked a few clarifying questions and I'll let you know if my inference changes. He also went on to indicate a lower pressure could make more sense if I'm getting too much flow reduction with 8 psi above clean. So I think I'm sticking to your guideline of 25% pressure increase.

Chris