Air Leak on discharge side has me stumped

May 16, 2015
6
Little Rock, AR
I have an air leak that is very small and hard to find. After leaving my pool off for 14 hours over the night, I start the pump. There is no air in my basket strainer and the pump is primed and ready to go, so no on the suction side leak. There is no water on my dry cement under any pipes, pumps, or filter. After starting the pump, I look in the pool, and about 1/4 air and 3/4 water come out of my returns lines for about 1-2 seconds then stop completely for the remaining 10 hours of operations. I do notice a few air bubbles coming from my Polaris hook up in the middle of the pool but it is very inconsistent but does continue through out the day and by air leak i mean the smallest smallest bubbles you wouldn't see unless you were looking for them. I have a salt water pool and I know they create bubbles but not to this extent. This started happening about two weeks ago and has not gotten worse but it just annoys me that their is an air leak I cant find it. I'm thinking it must be the filter even though my filter gauge is rock steady or something having to do with my Polaris pump but there is no water anywhere in plain view. Also when I turn the pump on I think i hear the air getting flushed from the piping but cant figure out if it is before or after the filter. If you can help me figure this out it would be great. My buddy who has had a pool for years longer than me says I will never find it without replacing everything and just wait until it gets bad enough to where it is easier to pin point. Any thoughts from the pool pros. One more thing, I am not losing any water at all from the pool.
 
Welcome to TFP!

The two most obvious places to look are: A slightly low water level can sometimes allow a votex to form in the skimmer, drawing air down into the plumbing. Also, check the seal on the pump strainer basket lid. Watch for nicks or cuts and make sure the two surfaces it presses against are clean and flat.
 
Long shot, but since it happened to me...

How hard is your airbleed to close? Something went screwy with the O-ring in mine. I never lost prime, I never saw a single drip, but yet my tank ended up full of air. I experimented and discovered the air entered when the pump was off. Bleed it as soon as it starts and bleed again 3 or 4 hours later, no air. Next day, air. I think that under pressure the O-ring got shoved into position, but when off, it got sucked down somehow and let the tiniest air leak begin. Then gravity drained the water out and sucked air in.

How did I fix it? Beats me. But when the air bleed stopped fighting me when I tried to close it, so did the air leak.
 
Long shot, but since it happened to me...

How hard is your airbleed to close? Something went screwy with the O-ring in mine. I never lost prime, I never saw a single drip, but yet my tank ended up full of air. I experimented and discovered the air entered when the pump was off. Bleed it as soon as it starts and bleed again 3 or 4 hours later, no air. Next day, air. I think that under pressure the O-ring got shoved into position, but when off, it got sucked down somehow and let the tiniest air leak begin. Then gravity drained the water out and sucked air in.

How did I fix it? Beats me. But when the air bleed stopped fighting me when I tried to close it, so did the air leak.
If your talking about the airbleed on my filter I don't have one. Just a Hayward pro sand filter. That is what makes this a bear. I think it only happens when my pump is off. Could it have anything to do with my Polaris because the Polaris hook upin the pool is the only place I have air coming out of. Just a very small amount but maybe after a full night it builds up.
 
So if the air is not in my basket and the pool levels are good it must be coming from the suction side of my pump prior to the impeller because air leaks come from the suction side and water leaks come from pressure side right and that is where the system changes over?? I love a challenge. I will win air leak,, I will win.
 
Probably a bad multiport gasket or a sticky diverter stem. I would recommend taking the multiport apart and checking the gasket. Before reassembling, clean and lubricate the stem o ring.

When the pump is on, the pressure pushes down on the diverter. But, when the pump is off, the water in the filter tries to go back down to pool level. This creates suction which pulles air in from the waste line.
 
I was beginning to think the same thing. I fixed it. At least for the last two days and counting. My jandy saltwater converter which sits down stream from the filter was leaking air when the pump was off at the connection where my temp salt indicator and flow indicator was. I don't understand the dynamics at work but it sounded like that was where the air started to come from when I put my ear on the pipe and turned off the pump. I reseated and lubed the small o-ring as well as the bigger o-ring that the sensor attached to and no more air. Still don't know of why under pressure it didn't leak being on the discharge side but it's good to go. Thanks for all the help guys. Gave me a lot to think about next time I have a air leak on the discharge side without a dripping pipe connection
 

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