I just finished up cleaning my cartridges and after reassembling the filter, I have an issue where when the pump primes, the pressure reading on my gauge goes to 12-15 for about 5 seconds, then steadily decreases all the way down to 0. If I open the air valve while priming, water eventually rushes out at high pressure, so I close the valve. Then the PSI reading slowly trickles down, and if I open the valve at that point, the water pressure out of the top is definitely lower. One time I was even able to open the valve fully after I shut the pump off, and water did not drain out of the tank, even when I removed the entire air valve assembly at the top. The gauge is a glycerin filled gauge, and I have similar pressure reading even with the old cheap gauge I used before I replaced the gauge. What could I be missing, as I hosed off anything on the inside of the filter housing that might be blocking that small outlet at the top of the lid.
Cartridge filter drops pressure quickly when starting
- Thread starter jman1865
- Start date
Hey Jman and SUPER belated Welcome !!!!
Sounds like you are missing the VS pump decreasing in RPMs (in steps) after prime. Your electric meter drops drastically also, and its a GREAT thing. Ramp up the RPMs and see if the PSI goes up. If so, you are golden and go back the way it was.
Sounds like you are missing the VS pump decreasing in RPMs (in steps) after prime. Your electric meter drops drastically also, and its a GREAT thing. Ramp up the RPMs and see if the PSI goes up. If so, you are golden and go back the way it was.
j,
Your missing how large filters work...
My filter pressure is about 1 lb. on a 30 lb. gauge when my pump is running at 1200 RPM. My SWCG works and my skimmers work. Makes me smile.
The gauge shows how much effort it takes to push water through the filter. It is not an indication of how well your pump is working. The lower the pump speed, the easier it is to move water through the filter, and the lower the filter pressure is going to be.
As long as you have a good flow out of your pool returns, a low filter pressure is a good thing.
Thanks,
Jim R.
- Nov 12, 2017
- 12,631
- Pool Size
- 12300
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-40
No water would flow out of the top of the filter with the pump off. The plumbing system doesn't retain pressure in it, it equalizes to atmospheric pressure when the pump stops. Think about it, both ends of your plumbing, inlet and outlet, are open to the pool. There's nothing trapping or creating pressure in the plumbing when the pump is off.
But water shouldn't leave the system either, the filter and pump and the pipes should stay full of water. If you open the air valve on the filter with the pump off, that "breaks the seal" and will let air into your filter and possibly the rest of the pool plumbing as well if you leave it open long enough. Then when you restart the pump, some of the air you just let in will get trapped in the filter, which you have to bleed off again by opening the valve again. By fooling with it, you might be creating the problem, which isn't really a problem so much as expected behavior.
Start the pump. Let the pump finish priming. Open the valve to bleed off any trapped air. Close the valve. Done. Leave it alone.
If you come back days later, after the pump has cycled on and off a few times from normal scheduling, you can check how it's doing. While the pump is running, open the valve. You should get no air, just water. That's how it should work. That's how mine works, anyway.
With no trapped air, and pump running at 1500RPM, I get about 5psi. I can expect that to rise a bit throughout the season. That's the indicator that my filter is capturing crud. That's all normal. The more the filter membranes get blocked by crud, the harder it is for the water to get through, so that increases the pressure in the system. I use the pressure gauge to monitor the filter's condition. When it increases a few pounds, I know it's time to clean the filter again.
When I open up my pump to clean out its leaf basket, that also lets air into the plumbing. I clean the basket, put it back into the pump, close it all up, then start the pump to watch it prime and fill with water. But now I've got some trapped air. So I open the filter valve and bleed it off until I get water spraying out, then I close the filter valve. Done. I don't fool with the valve again until I clean the pump basket again.
But water shouldn't leave the system either, the filter and pump and the pipes should stay full of water. If you open the air valve on the filter with the pump off, that "breaks the seal" and will let air into your filter and possibly the rest of the pool plumbing as well if you leave it open long enough. Then when you restart the pump, some of the air you just let in will get trapped in the filter, which you have to bleed off again by opening the valve again. By fooling with it, you might be creating the problem, which isn't really a problem so much as expected behavior.
Start the pump. Let the pump finish priming. Open the valve to bleed off any trapped air. Close the valve. Done. Leave it alone.
If you come back days later, after the pump has cycled on and off a few times from normal scheduling, you can check how it's doing. While the pump is running, open the valve. You should get no air, just water. That's how it should work. That's how mine works, anyway.
With no trapped air, and pump running at 1500RPM, I get about 5psi. I can expect that to rise a bit throughout the season. That's the indicator that my filter is capturing crud. That's all normal. The more the filter membranes get blocked by crud, the harder it is for the water to get through, so that increases the pressure in the system. I use the pressure gauge to monitor the filter's condition. When it increases a few pounds, I know it's time to clean the filter again.
When I open up my pump to clean out its leaf basket, that also lets air into the plumbing. I clean the basket, put it back into the pump, close it all up, then start the pump to watch it prime and fill with water. But now I've got some trapped air. So I open the filter valve and bleed it off until I get water spraying out, then I close the filter valve. Done. I don't fool with the valve again until I clean the pump basket again.
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I do understand how the pump/filter should work. The concern I have is that the pressure is not great from the returns to the pool. During one test, I turned off the pump, and removed the entire pressure relief assembly from the top of the filter tank, and no air entered the system (could not hear any water clearing out of the pipes/filter canister). It seems to be that there might be a blockage of some type because I was able to press on the mesh screen from the open port (when I removed the bleeder assembly entirely) and introduce air back in to the filter housing, and after that water left the system as expected. It just seems weird to me that after a full cleaning of the filter I would have these intermittent pressure issues. The drop I am speaking of occurred while the pump was still priming (no change in speed from the variable speed pump - I am aware that the pump speeds would necessarily reduce pressure inside the system once the priming cycle is complete. I am having the PSI drop for 15 to 1 or less while the full speed prime cycle is still going on - eventually the pump considers itself primed, and does drop to normal speeds.
- Nov 12, 2017
- 12,631
- Pool Size
- 12300
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-40
Then perhaps you assembled the filter incorrectly, which is not hard to do. Or not everything is seated correctly inside. The way mine goes together, it'd be possible to not have a good seal on the cartridges but still get the lid on, because there's a spring that kinda takes up some slack. If you want to pursue that possibility, obtain a parts drawing of your model filter, and reassemble it following the drawing carefully.
If you have low pressure at the filter (which suggests there is no blockage anywhere) and weak flow at the returns and no leaks, then I'd say that's just a matter of your flow rate (RPM setting). If your pump is ramped up and the pressure gauge is high, with weak flow at the returns, then that suggests a blockage somewhere or a dirty filter. That's the extent of my knowledge, so I can't explain the symptom of falling pressure during the prime (I can't say if that's normal or not, though it didn't seem to concern Jim, who would know more about it than me). Or try replacing the gauge, with new, not old, to eliminate that possibility.
What makes you think your flow is weak? Are you comparing it to how it used to feel? At 1500RPM, I'm not getting strong flow out of my returns. It's divided by three returns, so there's that.
If you have low pressure at the filter (which suggests there is no blockage anywhere) and weak flow at the returns and no leaks, then I'd say that's just a matter of your flow rate (RPM setting). If your pump is ramped up and the pressure gauge is high, with weak flow at the returns, then that suggests a blockage somewhere or a dirty filter. That's the extent of my knowledge, so I can't explain the symptom of falling pressure during the prime (I can't say if that's normal or not, though it didn't seem to concern Jim, who would know more about it than me). Or try replacing the gauge, with new, not old, to eliminate that possibility.
What makes you think your flow is weak? Are you comparing it to how it used to feel? At 1500RPM, I'm not getting strong flow out of my returns. It's divided by three returns, so there's that.
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Follow up to this - the issue appears to have been a problem with my pressure relief valve. I replaced it (due to hearing a whistling noise from it after further testing), and the PSI readings stay steady at 4-5 PSI, which is consistent with historical performance out of this filter. Hope this helps anyone else with this type of issue in the future - it could be any component in the ecosystem.
