Expectations on PSI ?

[cody21]

Our PSI seems really low. When booster pump kicks on, it drops to around 5 PSI. When OFF, it's around 8 PSI .. How do we determine what it SHOULD be? Is it based on the Pump and Filter combo? E.g, if the PENTAIR pump has a specific rating (1.5HP) , is there some math we can apply that says what the PSI should be ? 7-8 PSI seems really low. When the filter and basket are dirty, it runs close to 20. I just cleaned the filter. And now it's low.

 

[ajw22]

If your PSI is not 0 when your pump is OFF, your gauge is broken and needs replacement.

Replace it with a 30 PSI gauge like this…

Bottom-mounted Pressure Gauge

tftestkits.net

The PSI depends on the plumbing and equipment. Every pool is unique.

Replace the gauge, clean your filter, and then let’s discuss what your clean filter pressure is.

 

[Jimrahbe]

Cody,

I have a 3 HP IntelliFlo pump and a large cartridge filter with a 30 lb. gauge.. I run my pump at 1200 rpm, most of the time. My filter pressure is 1 or 2 lbs...

Filter pressure is not a reading of how well your pump is running, it is a measure of how hard it is to push water through your filter.. As long as you have good flow, lower pressure is always better..

This is also why your pressure goes up as the filter gets dirty.

Thanks,

Jim R.

 

[cody21]

Got it. It just seemed low to me. and from previous comment, I was referring to the BOOSTER pump being off. Mr the main Pump). Thanks

 

[ajw22]

Got it. It just seemed low to me. and from previous comment, I was referring to the BOOSTER pump being off. Mr the main Pump). Thanks

I am lost as to what comment you are referring to.

The booster pump is after the filter and booster ON or OFF does not affect the filter PSI.

 

[Dirk]

Our PSI seems really low. When booster pump kicks on, it drops to around 5 PSI. When OFF, it's around 8 PSI ..

I think the booster pump would affect the filter pressure, because it is drawing water from after the filter (or should be). That would look to the gauge as less total resistance, which should drop your filter gauge reading. That's just my hypothesis, but it's born out by your experience. No matter, as Jim points out, less pressure is better.

How do we determine what it SHOULD be? Is it based on the Pump and Filter combo? E.g, if the PENTAIR pump has a specific rating (1.5HP) , is there some math we can apply that says what the PSI should be ?

There is some math, no doubt, but it's not just about the pump and filter. Every pipe in your entire system, its diameter and length and slope, every elbow, every component along the way (filter, heater, check valve, etc) affects flow and pressure. You can see why you're being told every pool is different, and why the math would be challenging to calculate. And since you can't observe the underground pipes and elbows, it'd be pretty much impossible to calculate at this point.

7-8 PSI seems really low. When the filter and basket are dirty, it runs close to 20. I just cleaned the filter. And now it's low.

That is all normal and expected. I run about 5 psi. 7-8 is not "really low" at all.

So while the math would be challenging, you don't need any to "calculate" your normal pressure. It's simple. You clean your filter, your pump basket and your skimmer basket(s), turn off any water features, turn off the booster pump, and then observe the gauge. That's it! That's your "clean filter" pressure reading. Then you regularly check your gauge (once a week is fine), under the same conditions (same RPM, clean pump and skimmer baskets, no booster). When the reading gets to be 20-25% higher than your "clean filter" pressure reading, it's time to clean your filter. Letting it get to 20 psi is not ideal. It just puts unnecessary wear and tear on your system, and costs you more money (in pump energy).

That's the general rule. You can clean your filter more often, if you like, but keep in mind it is the cleaning of a filter cartridge that wears it out more than anything else. Plus, a little "dust" on the cartridge membranes actually helps it filter better. Obsessively cleaning a filter is not necessary and is counter productive. So too often or not often enough are both less than ideal, use the 20-25% rule and you'll be fine.

 

[cody21]

So I have an update. Turns out the BASKET had more (SPRING time) tree debris in it than I anticipated - So today I decided to remove it and give it a good cleaning - and viola, pressure is back up to normal (around 8 PSI).

I do have a side question - anyone have a technique to remove the pump's BASKET without having to drain the filter ? The problem I run into is when I drain the filter to get the water level in the BASKET low enough to remove, the back-flow ends up sending debris backwards - back into the intake line. When air finally arrives into the basket for me to remove, the debris is already "out there". So when I clean & replace everything, the basket immediately gets debris in it that was in the line. I'd like to be able to just NOT DRAIN the filter, turn off the Intake line and remove the basket to clean. But every time I do that I flood the floor. Any hints on how to do this without making a mess? Thanks again everyone.

 

[mknauss]

You either need a valve between the filter and pump or you need to close the suction valve located before the pump. Depends on what type of valving you have.

 

[cody21]

You either need a valve between the filter and pump or you need to close the suction valve located before the pump. Depends on what type of valving you have.

Yea, we only have the Suction valve BEFORE the pump ... I try to partially close it to slow the flow, but it's just not enough to prevent the backflow as air gores out of the Filter. I like your idea though of a valve between filter & pump ... I might try to engineer that. Thanks !! You guys are the best.

 

[cody21]

I think the booster pump would affect the filter pressure, because it is drawing water from after the filter (or should be). That would look to the gauge as less total resistance, which should drop your filter gauge reading. That's just my hypothesis, but it's born out by your experience. No matter, as Jim points out, less pressure is better.


There is some math, no doubt, but it's not just about the pump and filter. Every pipe in your entire system, its diameter and length and slope, every elbow, every component along the way (filter, heater, check valve, etc) affects flow and pressure. You can see why you're being told every pool is different, and why the math would be challenging to calculate. And since you can't observe the underground pipes and elbows, it'd be pretty much impossible to calculate at this point.


That is all normal and expected. I run about 5 psi. 7-8 is not "really low" at all.

So while the math would be challenging, you don't need any to "calculate" your normal pressure. It's simple. You clean your filter, your pump basket and your skimmer basket(s), turn off any water features, turn off the booster pump, and then observe the gauge. That's it! That's your "clean filter" pressure reading. Then you regularly check your gauge (once a week is fine), under the same conditions (same RPM, clean pump and skimmer baskets, no booster). When the reading gets to be 20-25% higher than your "clean filter" pressure reading, it's time to clean your filter. Letting it get to 20 psi is not ideal. It just puts unnecessary wear and tear on your system, and costs you more money (in pump energy).

That's the general rule. You can clean your filter more often, if you like, but keep in mind it is the cleaning of a filter cartridge that wears it out more than anything else. Plus, a little "dust" on the cartridge membranes actually helps it filter better. Obsessively cleaning a filter is not necessary and is counter productive. So too often or not often enough are both less than ideal, use the 20-25% rule and you'll be fine.

Thank you ... Makes sense.