Become a TFP Supporter Welcome to our new server and new forum software. Pool School
Results 1 to 12 of 12

Thread: Pool filter loses prime when shut off

  1. #1
    Junior Member
    Join Date
    Sep 2010
    Posts
    5

    Pool filter loses prime when shut off

    I have a 14 year old pool with a hayward super pump and a triton tr-60 sand filter. Pump was new last year with new attachments (impeller etc.) up to the basket housing. I run the filter about 10 hours at night on a timer. I noticed a few weeks ago that the pump was running dry. I do not know how long it ran like that but it could have been a few days. I reprimed it and ran it. I noticed the filter was "sweating water" on the outside of the casing. When I wiped it off, water immediately seeped out. I figured this may also let air in when the filter is shut off so I bought a new triton tr-60 sand filter because the specs on the new one matched the old one and I figured it would match up to the existing plumbing. Well the fittings on the new one were approx 1 inch higher so I had to cut the pipes where necessary to raise the plumbing 1 inch to attach the new filter. I primed the pump and everything ran fine. When I shut the pump off I could hear the filter immediately start to drain water. If I restart the pump within a couple of minutes the pump will prime but there is already alot of air that needs to be bled out of the valve on top of the filter. If I restart is after a couple of minutes the pump has already lost its prime. I have checked for air leaks at all the normal places, I have tried the shaving cream trick on all fittings. I have changed the seals on the backwash valve, jandy valve and pump basket lid. I have looked for water leaks when turning system on and off and listened for any air leaks. When I prime the pump it immediately sucks the water out of the basket housing and when primed it runs at 12 psi. Filter system will run with no problems, no bubbles in pool until I turn it off. Right now I run the system for 2 days straight and turn it off for 2 days, reprime and run again for 2 days etc. I have not been able to get a good explaination on how this system prevents the water from draining out and losing prime when shut off. I need some troubleshooting help if possible to prevent just changing major parts until its fixed. I cannot see any wet spots on the ground that might indicate any inground plumbing leaks. I would appreciate any help or advice that can be offered on how to proceed. I have attached pictures to show the system I have. Photo 154 shows the original plumbing and the problem I had with the new filter install. Photo 170 shows the new filter installed with the modified plumping, photo 165 shows the pool itself for reference. Thanks in advance for any help.
    Attached Images Attached Images
    Intex 20'x48" round ultra metal frame pool
    Vinyl pool walls
    10,000 gallons (appox.)
    1500 gallon filter pump w/ Saltwater Water Sanitizing System

  2. #2
    Mod Squad Bama Rambler's Avatar
    Join Date
    Jun 2009
    Location
    SouthWest Alabama
    Posts
    20,973

    Re: Pool filter loses prime when shut off

    The top of that filter should have an air bleed valve. Does it get any air in it after running the system a while?
    Is the skimmer weir working freely?
    Is the water level in the pool lower than normal?
    Dave J. TFP Moderator
    24' x 52" Round AGP. 1.5hp Dynamo pump. 24" Pentair Sand Dollar Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit
    You can stop SLAMing your pool when you pass the OCLT (You lose 1ppm or less FC overnight, & You have .5ppm CC's or less) & your water is clear.

  3. #3
    Guest

    Re: Pool filter loses prime when shut off

    What happens when you d/c the pool cleaner?

  4. #4
    Senior Member In the Industry

    Join Date
    Apr 2007
    Location
    Raleigh, NC
    Posts
    21,901

    Re: Pool filter loses prime when shut off

    Welcome to the forum

    To my knowledge, the only way you can lose prime when the pump is off is an air leak. Since there is no visible water leak with the pump running it is almost surely a suction side leak.

    Starting with the pump strainer basket lid, going to the pump strainer basket drain plugs, and then working your way through the Jandy valve, you should find it.
    Dave S.
    Site Owner 42k vinyl and concrete pool, 1.5hp pump, 140gpm filter, No SWG
    TFTestkits owner
    TFTestkits , PoolMath , Pool School

  5. #5
    Junior Member
    Join Date
    Sep 2010
    Posts
    5

    Re: Pool filter loses prime when shut off

    Pool water level is normal, pool has a auto filler like a toilet bowl float. Skimmer Weir operates freely. When the system is primed and running there is no air in system, even from the air bleed valve as long as the system stays running. When I shut it off I can immediately hear water draining from the filter and plumbing. If I start is up within a couple of minutes, the pump will prime itself but there will already be air that needs to be bled from the filter bleed valve. If I wait more than a couple of minutes to restart the pump it is already running dry and needs manual priming. I have tried to turning the jandy valve to isolate the cleaner and I have the same issue. I have not tried disconnecting the cleaner but I will, it may take a few day for me to get to that since it is now dark when I get home from work. I will update asap. My question is: How is this system designed to hold the prime when shut off? Does the system create a vacuum in the filter to hold water in? What prevents the water from just draining into the pool on the return side when shut off? I am hoping that if I can better understand how the system is designed to work, I may be better able to deduce where the problem is. I am hoping I do not need to dig up all the plumbing underground. Thanks to all who are trying to help me. It is much appreciated.
    Intex 20'x48" round ultra metal frame pool
    Vinyl pool walls
    10,000 gallons (appox.)
    1500 gallon filter pump w/ Saltwater Water Sanitizing System

  6. #6
    Mod Squad Bama Rambler's Avatar
    Join Date
    Jun 2009
    Location
    SouthWest Alabama
    Posts
    20,973

    Re: Pool filter loses prime when shut off

    The system is designed to have a static zero head when the pump is off and the vacuum created in the filter with no air in it holds it full of water. When there are no leaks the system will stay full.

    Turn off your autofill and run the pool a few days and see if you're losing water. I suspect you have a leak somewhere in the discharge piping that either seals off when under pressure or you just haven't found it yet.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 1.5hp Dynamo pump. 24" Pentair Sand Dollar Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit
    You can stop SLAMing your pool when you pass the OCLT (You lose 1ppm or less FC overnight, & You have .5ppm CC's or less) & your water is clear.

  7. #7
    Junior Member
    Join Date
    Aug 2010
    Posts
    10

    Re: Pool filter loses prime when shut off

    I see you have a polaris 360 for your cleaner, but what is that thing in the background that appears to be attached to the skimmer? Have you tried pulling that off? Have your tried positioning your suction valve at the pump to either 1 of the two positions rather than at some midspot it seems to be in in the pics?

    dave mc

  8. #8
    Junior Member
    Join Date
    Sep 2010
    Posts
    5

    Re: Pool filter loses prime when shut off

    The cleaner is actually a Hayward Navigator, the thing next to the skimmer is called a "frog log". Its allows small critters that fall into the pool to get themselves out. It actually works great, I have not had a dead animal in the pool for a few years now, I have had alot of dead lizards and ground squirrels in the past (I live in Phoenix, Az). It is not attached to anything it just sits by the skimmer and does not seem to affect anything. Anyways I primed and started the pump/filter last night to let it run for a few days. I took a half hour to get it primed thats how dry it was. If I move the jandy valve to shut off either the cleaner or the skimmer there is no difference, as soon as I turn the pump off the entire system starts draining. I am going let the pump run until Sat without shutting it off so the pool stays clean. It is too hard to check for leaks after priming it since the hose gets water everywhere when doing so. By Sat everything will be dry and I will have more time to work on it. One thought that popped into my head was that the 3 hedges that are planted in front of the wall surrounding the filter assembly may have grown roots that may have damaged underground plumbing and that may be why I cannot see anything. I will start digging to expose as much of it as I can and I will start working on removing those bushes roots and all. Finding the cause of the leak in this system has been one of the most frustrating things I have ever attempted to fix. Thanks again for the help and advice.
    Intex 20'x48" round ultra metal frame pool
    Vinyl pool walls
    10,000 gallons (appox.)
    1500 gallon filter pump w/ Saltwater Water Sanitizing System

  9. #9
    Mod Squad Bama Rambler's Avatar
    Join Date
    Jun 2009
    Location
    SouthWest Alabama
    Posts
    20,973

    Re: Pool filter loses prime when shut off

    If it gets too much for you, you can call a leak detection company to come tell you where the leak is. I'd exhaust all other means before that though.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 1.5hp Dynamo pump. 24" Pentair Sand Dollar Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit
    You can stop SLAMing your pool when you pass the OCLT (You lose 1ppm or less FC overnight, & You have .5ppm CC's or less) & your water is clear.

  10. #10
    Senior Member 4JawChuck's Avatar
    Join Date
    Jun 2010
    Location
    Winnipeg, Manitoba, Canada
    Posts
    223

    Re: Pool filter loses prime when shut off

    When you say "loses its prime" do you mean that it will not pump water without manually filling the pump basket?

    If I shut my pump off at night and restart in the AM it takes a few seconds of running before full water flow is established and I get pressure to the filter (enough to let the heater light off).

    Since I have no check valve in my system I assume this is normal, I don't see a check in yours either and pumps are always above water level on the installs I have seen. The pump basket is designed to hold an amount of water in the basket area to allow the pump to prime itself and prevent dry starts on the mechanical seal, this amount of water should be enough to get water flowing in the system but it does take 30 seconds or so to get going.

    The only way I can keep my filter basket full of water is by shutting off the suction line valve and return valve to seal the pump and sand filter into a closed system. The water height above the pump in the sand filter will naturally drain water out of the filter sucking air through the mechanical seal which will drain the pump of water to the suction side plumbing line, it other words your filter basket will only be half full of water in the AM.

    This is normal on a worn mechanical seal/pump although my system stays full for a few hours or more. Your seal maybe very worn and on its way out although it may not leak water yet. If it self primes I wouldn't worry about it until the seal starts to drip, might be a good idea to change the seal now or have the part on hand for when it does fail...its only a couple hour job to replace assuming your handy and follow the directions that come with the seal (don't start it dry!).

    Can you verify it self primes or not? There should be no way for the water level in the basket strainer to be below the suction side line unless you have a leak in the pump body, this should be enough to prime it.
    55 Kilolitre in-ground 18'X36' vinyl lined kidney shape, 1HP pump, Jacuzzi 250lb sand filter, RayPak Delta T 200K BTU natural gas heater. New PoolWerks "Blue Diffusion" liner on May 26th-2011
    Avatar is my pool!

  11. #11
    Junior Member
    Join Date
    Sep 2010
    Posts
    5

    Re: Pool filter loses prime when shut off

    Leak is fixed! After running the pump for several days constantly I was able to determine that the ground around all the pool equipment was completely dry so I figured there was no external leak. I tried moving the jandy valve to shut off the pool cleaner and draw water only from the skimmer. When I did this there were bubbles coming from the return lines in the pool. If I moved it off of skimmer only to either a mix of both or floor only, there were no bubbles. But no matter where the valve was set if I turned off the filter pump, the water immediately started draining out of the equipment and within 1 minute the pump needed to be primed again. Even after I would fill the pump basket housing with water the pump was very hard to prime. I decided to do what others suggested and take a hose and run the water all over the pump basket area while I shut off the system after repriming to see what happened. I avoided doing this before because it soaks everything including the ground and I was watching to see if any water leaked out of the equipment which is tough to do when everything is soaked. Well this turned out to be the solution because with the water running over the pump basket housing the sound of water draining out when the pump was shut off went away. When I removed the water flow the sound started and the system started draining. I let it drain and restarted. With the water running over the basket area the pump would self prime and I could bleed the air from the top of the filter. I reduced the area of the water flow to try to isolate exactly where the leak was. If I directed the flow to only the area where the pump attached to the basket housing, I got the same good result. I decided to try replacing the gasket between the motor and the housing. When I went to the pool store the guy suggested I also replace the pump seal assembly even though the pump was only 1 year old since I was unsure how long it had run dry. I was able to do that myself since I had done it before. So I bought a pump seal and the others came in a kit which included a seal for the pump to the housing, a diffuser seal and a basket lid seal. I had already replaced the lid seal since many said that was a good place to start. I filled the basket with water, put the lid on and turned the pump on and it primed immediately. After all the air was bled from the top of the filter I shut it off. The wonderful sound of silence followed. No water draining. I set the timer to let it run overnight and shut off in the am. Later the next day I went out to manually start it up after being off for half a day and it started right up with no air in system. I should have done the water trick with the hose in the beginning and it would have saved me alot of time. The pool forums definitely helped because most of the very experienced people were adament that an undergounnd plumbing leak was not common and I was about to push myself in that direction and start digging. So I was able to fix the leak with about $37.00 in parts and it took me no more than 1/2 hour to change the necessary seals. I wish to thank all those who took the time to read and respond to this post because I learned alot about my system and it will help me troubleshoot it in the future and maybe be able to help my neighbors save $ by fixing their own systems.
    Intex 20'x48" round ultra metal frame pool
    Vinyl pool walls
    10,000 gallons (appox.)
    1500 gallon filter pump w/ Saltwater Water Sanitizing System

  12. #12
    Junior Member
    Join Date
    Sep 2010
    Posts
    5

    Re: Pool filter loses prime when shut off

    I meant to mention to 4jawchuck in my last post that you mentioning that the pump should self prime without as much trouble as I was having led me to look at the pump more closely and sure enough when I replaced the pump seal the old on came out in 2 pieces on the impeller side. I think that may have been the main problem. Thanks for that! I can now work on something else on the weekends!
    Intex 20'x48" round ultra metal frame pool
    Vinyl pool walls
    10,000 gallons (appox.)
    1500 gallon filter pump w/ Saltwater Water Sanitizing System

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •