Air Pockets in Intake Tube - Intex AGP

[NY Smokeater]

Greetings,

I added a surface skimmer to my pool. The pool has 2 intake (return) holes and subsequent tubes. On the intake that does not have the skimmer, I have the issued hard plastic, mesh-like cover. Behind that is the plastic nipple which I believe restricts some of the flow to allow the pressure to remain "in the green" as well as allows enough suction for the skimmer to grab surface dirt.

Late last year, I noticed that the flow gauge on my sand filter was reading near 10psi, which is yellow on my gauge. To correct it, I researched and saw that others were creating an opening in the plastic nipple to allow the flow to be sufficient.

As a result, I've noticed a bunch of air in the return tube for the one side where the cut out nipple is. The return tube where the surface skimmer is located is fine. I can usually remove the air from the 1 tube by removing the nipple but I lose quite a bit of suction from the surface skimmer.

Am I missing something here? I certainly dont want the filter to work harder than it needs to but the surface skimmer does a fantastic job. Any guidance is greatly appreciated.

 

[Texas Splash]

Typically, when the filter pressure increases it's time for a backwash. The only way to really know when you should be backwashing is to know your clean (starting) pressure, and make note of when it increases by 25%. If the colored gauge/needles reflect that 25% increase, great. If not, just go by the numbers. If it happens quickly or a lot, you may have algae, so watch for that.

As for the nipple, I have a feeling you may have created a suction side air leak which will reduce suction and prime to the pump. You want the tubes and/or PVC from the skimmer/suction ports to be air-tight. Just like trying to drink from a straw with a crack in it - it doesn't work well.

 

[NY Smokeater]

Thank you Texas for the response.

The pressure rise only happened once last season. I attributed it to the nipple I put on. Had no idea it could be algae.

I usually backwash every 2 weeks. I don't know if that is overkill or not enough but luckily I had very few issues with chemistry or an overly dirty filter.

If this nipple is under water, where could I be introducing air to the tube? Could it be aeration from the hole in the nipple somehow created from the suction? I'm not quite sure how to prime air from a filter. Once I shut the filter off, the tube fills with water.

I suppose I need to re-search the forums to see how others have hooked up their surface skimmer and maintained sufficient suction to grab surface dirt.

 

[Texas Splash]

Usually an AGP remains fully primed since the water level is above the pump. So I suspect air is getting pulled-in from somewhere between the skimmer/suction lines and pump basket. You might take a look at our Suction Side Air Leaks - Trouble Free Pool page.

 

[NY Smokeater]

These were my thoughts as well which is why I'm perplexed. I had another read of that article (thank you) and simply do not understand how this issue is occurring. I am able to resolve the issue by removing the nipple from the one intake. The side effect of that is less suction for the skimmer. I will have another look at the o-ring on the filter strainer to see if that is the culprit. What I don't understand is that the air in the tube is prior to the screener.

I was just toying with the pump and noticed some bubbles from return jet. I also saw water coming from the small air vent that sits outside of the pool for the air vent. I re-tightened all of the fittings to see if one may have been the cause.

I will look into other surface skimmer setups tomorrow to see how I can retrace my steps

 

[Blacklisted]

These were my thoughts as well which is why I'm perplexed. I had another read of that article (thank you) and simply do not understand how this issue is occurring. I am able to resolve the issue by removing the nipple from the one intake. The side effect of that is less suction for the skimmer. I will have another look at the o-ring on the filter strainer to see if that is the culprit. What I don't understand is that the air in the tube is prior to the screener.

I was just toying with the pump and noticed some bubbles from return jet. I also saw water coming from the small air vent that sits outside of the pool for the air vent. I re-tightened all of the fittings to see if one may have been the cause.

I will look into other surface skimmer setups tomorrow to see how I can retrace my steps

Give this a try, the vents you are talking about are they the ones before the shutoff valve? I think they are a safety mechanism for entrapment. The pool should of come with caps for them when you vacuum. If not you can use automotive vacuum caps of the correct size, those ports will allow air to be sucked in if there is any restriction in the suction side. Just a thought for you to try.

 

[NY Smokeater]

Yes blacklisted, they are before the shut off valve. I found and put the cap under the intake without the skimmer on it. Definitely fixed the issue with the hose filling with air. I also noted that the pressure gauge on the sand filter is now reading at 2 or just below. I've attached a photo. Is this okay? I did notice it was slightly higher with the other cap that I had put a hole in.

One other note, I backwashed and rinsed just before putting the full cap on and had a low pump flow alarm sound. Is this all tied into the cap issue I may be experiencing or is that for another thread?

I appreciate the patience. This pool stuff is surely throwing me for a loop.

 

[Blacklisted]

Yes blacklisted, they are before the shut off valve. I found and put the cap under the intake without the skimmer on it. Definitely fixed the issue with the hose filling with air. I also noted that the pressure gauge on the sand filter is now reading at 2 or just below. I've attached a photo. Is this okay? I did notice it was slightly higher with the other cap that I had put a hole in.

One other note, I backwashed and rinsed just before putting the full cap on and had a low pump flow alarm sound. Is this all tied into the cap issue I may be experiencing or is that for another thread?

I appreciate the patience. This pool stuff is surely throwing me for a loop.

If you backwashed with the SWG on it will get a low flow alarm. As long as it went away you should be good. If your pressure is close to what it was that should be good. I know on mine it's a little higher because my filter is a little small for my pump.

Looks like that should take care of your problems with the sucking air. Let us know if there is any other questions.

 

[NY Smokeater]

Thanks for that tidbit about the low flow alarm while using the SWG. I was not aware of that. Is there anything wrong with backwashing using the SWG? Should I figure out how to bypass the SWG?

I noticed that after I put the cap on the intake, I was still getting some air. By the time my 5 hour filter run cycle was complete, 3/4 of the hose was filled with air. I double checked the hose clamp and adjusted & retightened both of them. Hopefully that solves this air concern.

It's been an awesome learning experience here so far. Many thanks again for this wonderful resource.

 

[Blacklisted]

I don't think it will hurt the SWG because it turns off when it gets the low flow. Do you have some pics of your hoses/filter setup you can post? You are still pulling air in from somewhere on the suction side. Hopefully tightening the fittings will eliminate the leak and you will be good to go.

 

[NY Smokeater]

Sorry for the delay. I was waiting to actually witness the filter running. Turns out, I adjusted the hose clamp and tightened it up and it appears this is where the air was entering. I had the clamp pretty tight and was surprised this is where air was getting into the hose.

I'm very pleased it was as minor as that. Thanks for the advice all.