False air suction

TomBonaire

Member
Feb 18, 2019
5
Bonaire
Hi, I have just installed an IGUI Waikiki 3,900 gallon pool. Pool plumbing consists of one skimmer and two return jets, connected by 2 inch piping. Please note the suction side is longer than the outlet side (60 feet compared to 40 feet). I connected an Intex 14 inch sand filter and an Intex 0.24 HP pool pump, because I thought I would need much power for the small pool. During system startup the pool pump catches air from the pool pump lid which causes the pump to run dry. However, when increasing resistance at the pressure side (from pool pump through filter to pool), either by vacuuming dirt or partially shutting a valve, the pump runs fine. What could be wrong?
My first thoughts were that the pump may not be able to handle the pressure difference and that results in problems at the pump.
 

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Welcome Tom! :wave: My initial thought is that with back-pressure applied to the pressure side, you are applying enough resistance that "may" be preventing water from flowing through the pump/filter easily, thereby allowing it to hold prime a little better. But the real question is why does the pump hold air under the lid at start up? I would ask these questions:
1 - Have you applied pool silicone to the O-ring under that clear lid? Also no defects on that O-ring?
2 - Is the pump below the water level of your above ground pool? Usually in these scenarios it is, therefore water naturally flows "down" to the pump letting it prime easily. In that was true, water would always fill that suction line, so the fact that the suction side is a little longer shouldn't matter.
3 - Have you checked all areas of the suction side for any potential air leaks? Look closely. It doesn't take much.
 

Jimrahbe

Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
14,639
Bedford, TX
Tom,

Welcome to TFP... A great place to learn all about pool operation, even if your island is owned by the Netherlands... :shark:

You don't have a pressure difference problem, you have a suction side air leak.. The first place to look is the pump basket O-Ring being bad or not lubed with "pool lube" or even just the lid not being tight.

Thanks,

Jim R.
 

TomBonaire

Member
Feb 18, 2019
5
Bonaire
Thank you all very much for the suggestions. I checked the pump lid and o-ring and all connections, but no leaks. I noticed however water spiralling down the skimmer. The skimmer only has a 2 inch pipe before it turns horizontal by a 90 degree bend. Could that be the cause of air being sucked in the suction line?
 

TomBonaire

Member
Feb 18, 2019
5
Bonaire
I am afraid that will not be possible. The vinyl pool wall of the IGUI pool reclines a few degrees, causing the skimmer not to be completely level, but inclining a little to the back. It is now filled to the back top (and being at the middle in the front). Is there another possibility other than replacing the skimmer?
 

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Is there another possibility other than replacing the skimmer?
In your case, based on the size of your pool, I'm not sure if that is an option worth attempting. If your pump is being starved for water, we suspect it's one of those two items though. Either not enough water in the skimmer which is then "gulping" air at the same time, or you have a small suction leak allowing air into the line "before" the pump. While you have a fairly long suction line (60') it should always be full of water since you have an above ground pool and water should be pushing downwards constantly. The only things I can think of are:
- Seeing if theere is a way to manipulate the skimmer from the outside to help "try" and level it more. Due to the shape of your shell, that may not be possible without taking a chance of breaking the skimmer or shell, so it may be something you have to live with.
- You noted that you checked the O-rings for leaks, but are they lubed with pool silicone? That is very important as well.
If your suction line is above ground, I suspect there are some couplers along the way. Perhaps check those connections as well with running water or wrapping with seran wrap.
- Last, with power disconnected from the pump, you might reach into the pump itself and check to ensure there is no debris stuck or wrapped around the impeller inside. You should be able to feel the impeller with your finger tips and turn it freely.
 

setsailsoon

LifeTime Supporter
TFP Guide
Oct 25, 2015
1,593
Stuart/FL
Thank you all very much for the suggestions. I checked the pump lid and o-ring and all connections, but no leaks. I noticed however water spiralling down the skimmer. The skimmer only has a 2 inch pipe before it turns horizontal by a 90 degree bend. Could that be the cause of air being sucked in the suction line?
For a new installation I'd contact the installer and tell them to correct the vortex in the skimmer. This is either due to a fabrication problem or an error with the installation. Also, call the manufacturer to see if they have a fix.

I hope this helps!

Chris
 

Jimrahbe

Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
14,639
Bedford, TX
Are you sure the weir door between the pool and the skimmer body is not just stuck up???

It should be impossible for the pump to suck all the water out of the skimmer unless not enough water is being allowed in.

Jim R.
 
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splashpad

Bronze Supporter
Aug 2, 2017
1,994
SE Kansas!
Your water level in the pool is too low. add water to the pool until the "tornado" stops in the skimmer.
Exactly what Duraleigh said, since the air goes away when you vacuum, you need to get more water into the skimmer box itself... Several mentioned if this is a new install, contact the installers.

.... The vinyl pool wall of the IGUI pool reclines a few degrees, causing the skimmer not to be completely level, but inclining a little to the back. It is now filled to the back top (and being at the middle in the front). Is there another possibility other than replacing the skimmer?
You mention "vinyl", but iGUi pools are fiberglass from a quick search... Is your pool material, Vinyl (is it soft flexible material) or fiberglass (is it a formed shape)?
 

TomBonaire

Member
Feb 18, 2019
5
Bonaire
We checked if sufficient water was allowed through the skimmer. The vortex was too small to allow air to be trapped in the suction line. Even when adding additional water directly to the skimmer by large garden hose, this made no difference. It seems therefore that not sufficient water supply to pump can be ruled out as a cause. The air in the pomp seems to be sucked in from the pressure side. After dismantling the pump, lubricating the shaft or ring and tightening the connection nut, the probleem seemed at first non-existent, but returned after a few minutes.
I therefore keep coming back to my initial thoughts that the pump has insufficient capacity. Feet of head will be 30-50 due to long piping and connections and although INTEX does not publish its pump curves (at least I have not been able to find it), this is apparently too much. I therefore consider changing the pump.
Regarding the side of the pool it is of course indeed fiberglass, sorry for the mistake.
 

Srqpoolguy

In The Industry
Feb 6, 2019
27
Sarasota fl
Check impeller of pump. May not be on all the way. I also vote a suction side leak somewhere. Even a small pin hole can cause issues. Make sure lid has no cracks etc. make sure nothing is restricting the lines. I have found everything from water bottles to rocks in suction lines . Don’t ask how it got there but it was. Good luck. Also check connection at front of pump where suction line enters.
 

setsailsoon

LifeTime Supporter
TFP Guide
Oct 25, 2015
1,593
Stuart/FL
The air in the pomp seems to be sucked in from the pressure side.
Air cannot be sucked in on the pressure side. A failure on the pressure side causes a water leak not air sucked in. Have you tried the immersion technique? Listen to your pump while you dribble a water hose on all the fittings and connections from the suction side of the pump back through the line to the pool connection. Any tiny crack or gap now sucks in water instead of air. This in turn causes a change to the sound of the pump. Where the dribble does this you will have identified the source. O-rings in covers are most typical but they can be anywhere. Drove me nuts one time 'till I found a hair-line crack in a strainer basket cover. Couldn't even see the crack but this technique found it. I couldn't see it but if you pressed the lid in the right place it was clearly leaking. Took it off and held it up to the sun then found the crack. Filled with glue and it worked 'till I could get the part. Now working perfectly.

I hope this helps.

Chris
 

TomBonaire

Member
Feb 18, 2019
5
Bonaire
Dear all, thank you again for thinking along. After several attempts to increase the water flow through the skimmer, suddenly the pool pump primed without sucking air. At that moment the water was normal and nothing to incfease the flow was done. Just many restarts of the pump. The pump kept working after that for a few days.

I was forced to lower the level of the water to add a valve and filled up the pool after the repair. Of course the same problem. I now decided to persist in focussing on priming the pump and not worry about water flow. Slowly the air sucked became less and the pump primed. Pump has been working flwalessly since the weekend. problem solved.

My lessons learnt:
- it seems the pump has just sufficient power to prime through the long piping
- intex pump is not self priming and this takes some effort
- combination of just sufficient water flow through skimmer (small vortex) and size of pump makes priming difficult.

And last but not least: all your suggestions and help were of lot use in solving problem. Thank you.
 
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