# Forum Home Renovation Pools, Spa & Water Features  Weird issue with air getting into the filtration flow pipes

## stube40

I have this weird issue with a sand-filter / salt-water chlorinator pool system. 
Basically, when the pump turns off sometimes (but not always) the water might drain out of the see-through pipe that contains the chlorinator cell. Sometimes only half the water drains out. Sometimes none. 
During operation, the see-through chlorinator pipe will fill up with water fairly quickly and operate as usual without any air bubbles in the chamber (except for maybe one or two the size of a 5c coin). Most of the time it stays this way until the pump switches off, but maybe 1 in 4 times an air bubble will build up in the see-through pipe around the chlorinator over a period of hours. Sometimes this will result in the chamber being only half-filled with water, which then can be noted in the salt-cell LCD display dropping from normal leve (about 104) to 93/94-ish and a red light comes on. When this happens, if I stop the pump then the water all drains out of the chlorinator chamber and I can hear a whole load of air bubbling to the surface in the pool through the skimmer box (I think). 
Any thoughts people? Something I should be concerned about? The pool seems to operate OK otherwise.

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## ringtail

I'd start by checking every place where air can get drawn in. Remove clean and lubricate any oring you can get to. Check the creepy hose for any cracks and any pipes that use rubber as a seal. I've found in the past that joins using rubber or orings can hold pressure but not a vacuum. Also check where the creepy goes into the skimmer box and make sure the water level high enough

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## stube40

Ah - good point. I always run with the creepy-crawly hose on and I think at the moment the level might just be only about 1/3rd of the way up the skimmer box, which means the angled-plastic fitting that couples the hose to the top of the skimmer box is about half-in, half-out of the water. I seem to recall that the angled fitting has a spring-loaded pressure-relief trap-door in it, so likely air can get in that way. 
I didn't think of that because I was focussing on the chlorinator / sand-filter / pump part of things. DUH!!!! 
I will try adding 10cm of water to the pool and see if the problem goes away. Will report back in the next few days. 
Thanks for replying!!

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## r3nov8or

you could test by running the system without the creepy. Your symptoms do sound like they may be aligned to slightly different water levels.e.g. is it OK after a big rain, but messes up after a backwash etc?

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## stube40

> you could test by running the system without the creepy. Your symptoms do sound like they may be aligned to slightly different water levels.e.g. is it OK after a big rain, but messes up after a backwash etc?

  Another good point - man, I feel so stupid now. I will run it this evening without the creepy and see what happens.

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## ringtail

My pool is really small so water level goes up and down quickly with evaporation /rain. If I'm running the creepy I have to really watch the water level. The plastic fitting you refer to pulls air in if partially exposed. And creepy hoses do crack with age too so have a good look at it.

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