No Pressure

bfr57

Member
Jun 6, 2011
15
I have an inground pool 15 years old. It has a 4 cartridge Pentair filter system with a Hayward pump and 1.5 HP single speed motor.
Last Sunday I cleaned the filters, restarted it, and had excellent flow and pressure was around 20psi. Walked away and didn't pay attention to the pool until Tuesday when I noticed very little flow and about 4psi. Can't figure out what's causing it. Here's what I've checked:
1. All baskets clean
2. Water level good (auto-level)
3. Moved valves to turn on/off the skimmers, creepy, and bottom returns in all possible configurations: no change. That tells me my lines are good in my thinking?
4. Inspected diffuser and impeller; all good.
5. Pump/motor all good.
6. Can see water in the pump filter basket
7. Replaced pump filter o-ring
8. Can't hear any suction noises
9. No water leaks on pressure side.
10. Opening pressure relief valve on top of filter housing produces low flow of water discharge.
11. Inspected above ground lines and don't see any defects
12. Sprayed full stream of water over valves to see if would change pressure; nothing
13. Did not take motor off pump as I didn't want to replace the ceramic seal if I don't have to.

Everything I've read my problem is on the suction side, but what am I missing here. Don't know where to go next.
Any ideas?
 

Dirk

Gold Supporter
TFP Guide
Nov 12, 2017
8,624
Central California
Pool Size
12300
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
You've certainly tried a lot! Troubleshooting 101 points to the filter. That's what you last altered. That's when the trouble began. I would disassemble it, and check what you see, and then reassemble it, using the owner manual as a guide (assuming it includes a diagram of the parts and how they go together). Don't rely on how you think it goes together, or even how it was. Something could have slipped out of place, or you assembled something incorrectly, etc. To me, that's the suspect, not a leak. I'm pretty sure a suction-side leak, or even a blockage, wouldn't increase filter pressure. But a problem with the filter could.

Or maybe something dislodged and impeded flow on the pressure side (after the filter). That, too, could increase filter pressure.
 
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Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
If the filter thing doesn't pan-out, a couple other things you might check:
- Weir door/flap is operating freely.
- Push water backwards from the pump to the skimmer just to ensure something didn't get partially stuck in there at some point.

If you don't make any progress, maybe post a pic or two of your equipment pad.
 

bfr57

Member
Jun 6, 2011
15
You've certainly tried a lot! Troubleshooting 101 points to the filter. That's what you last altered. That's when the trouble began. I would disassemble it, and check what you see, and then reassemble it, using the owner manual as a guide (assuming it includes a diagram of the parts and how they go together). Don't rely on how you think it goes together, or even how it was. Something could have slipped out of place, or you assembled something incorrectly, etc. To me, that's the suspect, not a leak. I'm pretty sure a suction-side leak, or even a blockage, wouldn't increase filter pressure. But a problem with the filter could.

Or maybe something dislodged and impeded flow on the pressure side (after the filter). That, too, could increase filter pressure.

I was always taught to go back to your last work when a new problem is introduced and wondered about the filters too. But why wouldn't opening the pressure relief valve on top on the housing cause the pressure to instantly increase if there was a problem with them? That valve is basically before the filters on the housing. I've had that filter housing apart more times than I can remember over the 15+ years and never had a problem like this before. Can't think of what could've gone wrong, but I'll tear it apart and double check.` If something was lodged after the filters, wouldn't pressure go up?
 
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bfr57

Member
Jun 6, 2011
15
If the filter thing doesn't pan-out, a couple other things you might check:
- Weir door/flap is operating freely.
- Push water backwards from the pump to the skimmer just to ensure something didn't get partially stuck in there at some point.

If you don't make any progress, maybe post a pic or two of your equipment pad.

Thanks, but I positioned all the manual suction valves shutting off/on the 3 different return lines; the floor drains, creepy floor cleaner and the skimmers. There wasn't 1 psi change. Not sure how to push water backwards on my system?
 

Dirk

Gold Supporter
TFP Guide
Nov 12, 2017
8,624
Central California
Pool Size
12300
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
If something was lodged after the filters, wouldn't pressure go up?
Yes, I would think so. I must have misread your original post. I thought you noticed low flow and a 4PSI rise. Which would indicate something blocking flow, either in the filter or after it. You're saying both your flow dropped and your pressure dropped, from 20 to 4PSI? Yah, that indicates blockage before the gauge, not after it, but couldn't that still be inside the filter? Or the motor is not performing as it did. Less voltage? Wiring problem? Breaker problem? Farfetched, but just hunting around with you... Do you have capability to test voltage, amps and/or watts?
 

bfr57

Member
Jun 6, 2011
15
Yes, I would think so. I must have misread your original post. I thought you noticed low flow and a 4PSI rise. Which would indicate something blocking flow, either in the filter or after it. You're saying both your flow dropped and your pressure dropped, from 20 to 4PSI? Yah, that indicates blockage before the gauge, not after it, but couldn't that still be inside the filter? Or the motor is not performing as it did. Less voltage? Wiring problem? Breaker problem? Farfetched, but just hunting around with you... Do you have capability to test voltage, amps and/or watts?

Yup, 4 psi constant; dropped from 20 psi. Flow also very low. Motor/pump sounds the same as it's always been. I do have ability to check voltage and amps, which will obviously give me watts.
 

HermanTX

Gold Supporter
May 20, 2020
1,401
Katy TX
Pool Size
14600
Surface
Plaster
Chlorine
Liquid Chlorine
Can you bypass the filter? I have a multiport valve in front of my filter so I can bypass it. If you do not, can you remove the cartridge filters and still run water through the filter (not sure how a cartridge filter is plumbed inside the housing). This would tell you if you have restriction in the filter or not. If you had blockage downstream of the filter you would see higher pressure (due to back pressure) but low flow. So my logic is indicating something between the pump and the outlet of the filter.
You also indicated you have full water in the pump basket so you are getting good suction.
Do you have a spigot on outlet of your pump? Can you remove it and put in your pressure gauge there to determine if you are matching the pressure you are reading on your filter.
 

wireform

Silver Supporter
In The Industry
Aug 15, 2017
1,979
Spring Valley, NY
If you're good with electricity check the amperage on the hot leg/legs of the pump circuit. See if the amperage matches close to the specs on the motor label. You also may have a capacitor issue.
 

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Just to answer your reply about not knowing how to push water backwards .... there's a couple ways. Insert a garden hose into the pump strainer pot where water enters from suction, wrap a rag around the hose in an effort to try and create a seal, then push water back towards the skimmer. Some people will grab a Drain King bladder or something like below to assist. Even though you tried various suction options, it doesn't take much to block flow.

My gut tells me that with both low flow and low psi you're experiencing either something in the line (blockage) or a problem at the pump. But try the tips noted above and let us know if you make any progress. Good luck.

 

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bfr57

Member
Jun 6, 2011
15
Thanks all. As seen in pic, I removed the pressure line from pump to filter and it’s all clear. But, broke the coupling nut putting it back together, Grrrrr. So to HD later and then I’ll check amp draw on motor. It didn’t sound like it was slower or struggling. Also some pics of the system. Oh, no spigot on my system.AE6F487C-DC08-414F-93B1-904D32856506.jpeg4F710201-6ED6-43F3-9505-1649940FC833.jpeg9E06D9DD-8659-4AC2-B311-9310955994DA.jpeg
 

bfr57

Member
Jun 6, 2011
15
Update. Got all the lines fixed. Started system back up and same pressure; 4 psi. Measured each leg of motor at 8 amps; all good there. So, removed all filters and started it back up; about 15 psi. A start! Inspected everything and found the o-ring at the bottom of filter "cross" that the filters all sit on was pinched and deformed. Got a new one, put it all back together, and wouldn't you know it, pressure at 30 psi. Ha, now actually a little high! Can't understand how that o-ring would cause low pressure as if it wasn't sealing, it would only suck water around the filters? So, lost on what was really the cause.
 

HermanTX

Gold Supporter
May 20, 2020
1,401
Katy TX
Pool Size
14600
Surface
Plaster
Chlorine
Liquid Chlorine
Your filter pressure gauge measures the back pressure your "filters" are creating in the system when water is flowing through the filter media. An unrestricted flow will be low back pressure and excessively high back pressure would indicate restriction in your filter medium i.e. clogged filter. That is why you need to clean your filters when pressure rises. But I think you stated you changed your filter cartridges.
You did not mention but how is the flow to the pool? Even with 30psi is the flow better than when it was 4 psi?
 

bfr57

Member
Jun 6, 2011
15
Your filter pressure gauge measures the back pressure your "filters" are creating in the system when water is flowing through the filter media. An unrestricted flow will be low back pressure and excessively high back pressure would indicate restriction in your filter medium i.e. clogged filter. That is why you need to clean your filters when pressure rises. But I think you stated you changed your filter cartridges.
You did not mention but how is the flow to the pool? Even with 30psi is the flow better than when it was 4 psi?

I just did a TSP clean on the filters; not new ones installed. These filters are only a year old; I usually get over 5 years on a set.
Bought these off Amazon; probably got what I paid for.....
So, flow is better, but not much, so I'm positive it's the filters now, as like you said, it's the sign.
Still scratching my head on the low pressure situation I had, but may never know!
Debating on switching over to a DE system before I pull the trigger on new filters. Need to do more research on that. Like I mentioned it's the original system that's 15+ YO.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
36,274
Laughlin, NV
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Chlorine
Salt Water Generator
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Can you post a full set of test results from your own test kit?
 

HermanTX

Gold Supporter
May 20, 2020
1,401
Katy TX
Pool Size
14600
Surface
Plaster
Chlorine
Liquid Chlorine
Debating on switching over to a DE system before I pull the trigger on new filters. Need to do more research on that.
I have a DE filter but there are many good reviews regarding cartridge filters with the added benefit you do not need to deal with the DE powder. I have recommended the use of cartridge filters to friends and relatives. It is a personal preference - either will do a good job.

Still scratching my head on the low pressure situation I had, but may never know!
Liquid will always take the path of least resistance. Just think about a leak in a wall or a overrun river bank. Water will flow to the least resistant path. If you had a bad seal or misalignment of your cartridge then that is where the fluid will go. With little to no resistance then you have no back pressure on your filter body thus the low pressure reading. The low flow could have been due to that restriction allowing only a minimal amount of flow.
Now that you have the filter cartridge in proper place, the flow has to go through the filter media. Therefore the higher pressure. But maybe the cartridge is bad. Not much can go wrong with a pool filter, it has some pipes & flow paths in it and it has a filter media - that is the main source of issues.

Also, is your gauge returning to zero when pump is off? Are you confident the gauge is properly functioning?
 
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