Baffled by air in vac line, lack of suction

[Diannapool22]

Hi TFP members,

Long time no see. I am at the end of my wits with my current situation, apologies in advance for the length. I recently replaced all the plumbing (above ground) at my equipment pad, including the expensive Hayward valve/ports coming off my Hayward pro series S244SV sand filter. I kept all PVC diameters and joints the same as previous layout. I removed, lubed and/or replaced every o-ring on my pump and filter lids/connections, and in-line leaf canister. No leaks, everything ran normal for a few weeks. Then my trusty old Navigator stopped running. It's 8+ years old and I've rebuilt it twice, so figured time to buck up and replace. Bought the Zodiac MX6, but after installing with new hose line and the Zodiac cyclonic leaf canister, it too would not run. I would find the vac floating near the top of the pool after the pump runs for a few hours. I read some reviews about customers receiving duds, so returned and purchased the Hayward Aquanaut instead, with a new Hayward vac line. The Aquanaut runs, although very slowly, and occasionally floats to the surface after several hours of the pump running. Something is creating air in the vac line...

My cousin is a pool guy and came over to take a look yesterday. Here's a rundown of what we know, working backward from the Aquanaut vac head:
-The Aquanaut and hose line are not the source of the air leak(s) (when totally submerged from end to end with pump off, there are no bubbles)
-The in-line leaf canister is not the source either (although serves as the visual point in which we can see air bubbles gathering)
-The suction in the skimmer basket (I only have one suction side port- this is where vac hose connects) seems strong, no vortex allowing air in due to hose connection there and appropriate water level
-The pump basket primes normally and when pump running there is almost no air under the lid, a tiny bubble maybe, that's always been there.
-The two returns are pushing water normally while pump is running with no air bubbles. However upon start up of pump there is definitely air in them that gets purged out, then settles down.
-I have not touched the pump except to check the impeller, which was in good condition. Buttoned up, no leaks we can see
-When I switch off the pump, you can hear a "whoosh" of water leaving the system and the water level in the pump basket goes down significantly

Incomplete conclusion- I have a suction side leak somewhere between my pump and the skimmer basket. I hope it's not underground, the only hypothesis I have left is the pump somewhow has an air leak. When I was rebuilding the plumbing, I needed to do a backwash and hooked up a garden hose, which was a bad idea as the water pressure is far too strong to use something of that narrow diameter and I'm wondering if the pump internals were damaged when I ran it. The pump is also extremely old and I've been hoping to string it along a bit longer. It is an old "Challenger" 3/4 single speed model. My only guess is somehow it's letting air in the system, otherwise it's an underground issue.

Questions- Is a pump air leak common? Do pumps crack or somehow contribute a small amount of air that compiles over the run time down the vac line? Why does the pump basket fill 99% full of water while it runs? What else should I troubleshoot? I don't want to spend $$$ on a new pump only to find out I still have another problem.

Thank you!

 

[ferretbone]

This is why I come to TFP, for these kinds of weird problems. I'm making a wild guess that air is creeping in from a valve on the suction side of the pump. Maybe even the nipple threaded into the suction side of the pump.
I'm 70ish% sure the air is not coming from much further down then right at the pump area.

After your pump ran for the day and has cut off, watch that pump pod for any air bubbles. Then fire it up, looking listening for air sucking sounds from the lid, the nipple, any valves on the suction side. Don't forget the drain plug on the pump pod up front. Infact remove that plug and seal it up very good first. Remember there is an oring just behind the pump pod where the pod and housing connect with 4 screws. Once you start openning the lid or pouring water into the pump, that place where those two connect will get wet and you'll never notice a leak there. Water or air. So do that first because this first test you will need a dry pad. Because the first sign of water is likely your air leak.

After your pump has ran for the day, or has ran long enough to clear all those bubbles, cut it off.
Next turn the pump on and off a few times looking for water splitting out of anything from the pump lid back into the suc line. If you see water dripping, leaking, squirting that's your air leak. Repeat this as needed until you feel like the pump area is not the leak. Don't open the lid yet. just keep popping the system by turn it on and off. I you have jandy valves or any valves remove the handles so you can see the water if any spitting from the middle.
Try that and see what you see.

 

[Jimrahbe]

When I switch off the pump, you can hear a "whoosh" of water leaving the system and the water level in the pump basket goes down significantly

When you switch the pump off, water should not drain back into the pool from the pump or the filter.

It is like when you put your thumb over the end of a straw in a glass of water. When you pull the straw out, the water will stay in the straw until you take you thumb off.

I agree with the ferret, you have an above ground air leak.

I also like his troubleshooting suggestions.

For me, I would look for why the pump drains back into the pool first, as I think that will solve all your problems.. Well maybe not your problems, but at least your pool problem.

Thanks,

Jim R.

 

[Diannapool22]

Hi @ferretbone and @Jimrahbe - thanks for chiming in, I am pretty desperate at this point. As luck would have it, there was some water seeping out the manual relief valve on top of my filter today. Pulled the valve, lubed the gasket, screwed it back in and it snapped in half on my last turn. Ordered a new one but will be a few days before it gets here. I will attempt the troubleshooting steps then. To make sure I'm understanding clearly, this is what you guys are suggesting:
1) After pump has run its cycle and is off, check the pump basket for bubbles (after the immediate whooshing sound when pump shuts off?) and turn pump back on, listen/look for leaks on suction side
2) Is the drain plug the small hand-turned valve on the front of the pump at the bottom? If so pull it out and seal that with what?
3) Open up the four screws and check the O-ring where pump pod meets housing? Then let everything dry?
4) Flip on/off watching for leaks or water spitting

Attaching a photo if helpful. Ironically the only plumbing I did not redo is the line into the pump basket (wasn't leaking and didn't want to dig/disturb it).

For the electricians out there, I am getting that J-box mounted on the block wall soon. Thanks again

 

[Jimrahbe]

22

The threaded connections into and out of the pump almost all leak after a few years.

I would never install a new pump without pump unions which rely on an O-ring rather than pipe goop or tape to make a good seal.

Thanks,

Jim R.

 

[ferretbone]

Hi @ferretbone and @Jimrahbe -


1) After pump has run its cycle and is off, check the pump basket for bubbles (after the immediate whooshing sound when pump shuts off?) and turn pump back on, listen/look for leaks on suction side
2) Is the drain plug the small hand-turned valve on the front of the pump at the bottom? If so pull it out and seal that with what?
3) Open up the four screws and check the O-ring where pump pod meets housing? Then let everything dry?
4) Flip on/off watching for leaks or water spitting

Yes for 1. Just see if new bubbles are coming in and if you can tell if they come from the botton, suction, or back of the pump.
Yes on 2. Remove it, lube the oring, and you can put a little telfon tape on the threads.
On 3. Just leave it be unless you see it leaking water, or can hear it sucking in air.
Yes on number 4.

After rereading your post and seeing your picture I'm wondering if you just need a good backwash. If the heavy down prime happens after you cut the pump off, that can be the sand filter. I'd open the filter up and just do a "deep clean" (not a sand change) then backwash. I'm thinking that is the biggest problem you have now. I have a filter that does what yours is doing after about 2-3 months, even when back washing twice a week. When I open the lid had flush the sand real good using my hands to break up the globs of junk in the sand, then backwash it stops for a few months. The filter has some tight plumbing between it and the pump return. You can do the deep clean while you filter is down.

 

[PoolStored]

If so pull it out and seal that with what?

Please use a silicone based lube like Magic Lube II on o-rings. Do not use a PTFE (teflon) based lube on o-rings. Inspect your your pump cover o-ring, and drain o-rings for cracking. I replace mine every year as they tend to crack w/in a year. If they are good, lube them with silicone lube.

 

[Dirk]

For testing above-ground suction-side air leaks:

 

[Dirk]

Another somewhat radical test to rule out the pump (that is a lot cheaper than buying a new one to troubleshoot the old one), is to temporarily replace the entire suction-side plumbing. You basically buy a PVC fitting that fits your pump, and enough PVC and elbows to run a line from the pump directly into the pool water. If running that reveals the same symptoms, you'll know it's the pump. If the symptoms go away, you'll know it's not the pump but somewhere before the pump.

In essence you'd be splitting your suction system in half, right at the suction port of the pump, to determine on which half the leak exists. Like I said, it's a bit off the wall, but for about $30 you'll be able to narrow down the search by 50%.

 

[Diannapool22]

Another somewhat radical test to rule out the pump (that is a lot cheaper than buying a new one to troubleshoot the old one), is to temporarily replace the entire suction-side plumbing. You basically buy a PVC fitting that fits your pump, and enough PVC and elbows to run a line from the pump directly into the pool water. If running that reveals the same symptoms, you'll know it's the pump. If the symptoms go away, you'll know it's not the pump but somewhere before the pump.

In essence you'd be splitting your suction system in half, right at the suction port of the pump, to determine on which half the leak exists. Like I said, it's a bit off the wall, but for about $30 you'll be able to narrow down the search by 50%.

Not a bad idea, thank you for the suggestion!

 

[Diannapool22]

Yes for 1. Just see if new bubbles are coming in and if you can tell if they come from the botton, suction, or back of the pump.
Yes on 2. Remove it, lube the oring, and you can put a little telfon tape on the threads.
On 3. Just leave it be unless you see it leaking water, or can hear it sucking in air.
Yes on number 4.

After rereading your post and seeing your picture I'm wondering if you just need a good backwash. If the heavy down prime happens after you cut the pump off, that can be the sand filter. I'd open the filter up and just do a "deep clean" (not a sand change) then backwash. I'm thinking that is the biggest problem you have now. I have a filter that does what yours is doing after about 2-3 months, even when back washing twice a week. When I open the lid had flush the sand real good using my hands to break up the globs of junk in the sand, then backwash it stops for a few months. The filter has some tight plumbing between it and the pump return. You can do the deep clean while you filter is down.

@ferretbone sorry for the delay, but a short update for you and any others following along. I scooped through as much sand as I could reach by hand and no globs of junk, in fact looked really clean to me. I do think it could use more sand in the filter but not sure that would contribute to my issue. After the part arrived, I ran a backwash for ~10 mins. Bought some magic lube 2, lubed up the filter lid gasket, the multi-port valve o-rings, as well as the pump plug up front and the one on the pump basket. Going on about 2 hours of running everything now and everything is working, although it STILL seems like more air than there should be in the leaf canister (the bubble continues to grow slowly as the pump runs, I am guessing in another hour or two my vac will be floating again. I know in this pic you'd think the leaf canister is leaking, but when I get rid of the bubble and hold it submerged, somehow bubbles are still forming. Which doesn't make sense to me if the canister is totally submerged how could it be the source of the air. I guess I could try a new leaf canister to rule it out completely. See pic of canister air level after about 2 hrs of run time.

Also- could tight plumbing from filter to pump contribute to air? The old plumbing looked like this nearly identically, but it could be a smidge tighter. Thank you for the help!

 

[Diannapool22]

For testing above-ground suction-side air leaks:

Dirk- I tried this test with the garden hose and the size of the air bubble does not vary. Looks like this regardless of water flow over each joint/potential air leak. Thanks again for the help

 

[Dirk]

@Jimrahbe, if air is collecting in the leaf canister while it is underwater, could there be some type of cavitation in the vac head?

@Diannapool22, just to confirm, when air was collecting in the leaf canister, was the pump running? At the normal speed for vacuuming? And was every bit of the vac hose underwater, or was some of it floating on the surface?

 

[Diannapool22]

@Jimrahbe, if air is collecting in the leaf canister while it is underwater, could there be some type of cavitation in the vac head?

@Diannapool22, just to confirm, when air was collecting in the leaf canister, was the pump running? At the normal speed for vacuuming? And was every bit of the vac hose underwater, or was some of it floating on the surface?

My cousin and I held the entire vac line (brand new), leaf canister (owned for 4 years), and vac head (brand new) entirely submerged with pump running at normal speed and bubbles were still appearing in the leaf canister. We tried removing the leaf canister, removing sections of hose, no improvement to the run speed of the vac. And this morning I found the vac floating after running its pump cycle last night. I still hear the "whoosh" of water leaving the pump when I shut it off. Something is up. Thanks Dirk!