air in pump, pressure/vacuum problems??

Hello all,
I seem to have a problem this year with my 30' AG pool that I have never had before.

this year for the first time, I decided to replace the sand in my sand filter. I have a 1hp pump with a 150 lb. sand filter. It has always worked fine.
this year after I changed the sand, it seems to have tiny air bubbles coming out of the return. This does not happen ALL the time, but quite often.

The pump pressure seems strong when skimming, about 14 psi.

I have an automatic vacuum, (an round aquatool brand) that has always worked fine. This year when I hook it up, it seems much less powerful, and whenever I hook it up, much more air comes out of the return, and the pressure goes down to 9psi.

In the filter basket, instead of being almost totally filled with water like it should, it seems to go down to about 1/2 full, so I can actually see the water pouring into the pump basket.

I rechecked and tightened all my hoses, and made sure they were ok. I do not think I have any leaks, but I'm stumped.

any suggestions??

Thanks, Frank D.

Did you check the O rings? Sometimes they have dirt on them, or they need to be lubricated to make a tight seal.

Thanks Marie,
I checked the o-ring on the pump filter basket top.....I did not check the o-ring on the top of the sand filter where that big lever is.....I'll do that.

Frank D.

I took the top off the sand filter and checked the o-ring. I also scooped a few handfuls of cottonwood cotton off the top of the new sand.
Retightened everything and backwashed, and vacuumed again. It was a tiny bit better, but the psi is still the same.........14 psi during regular skimming, and almost no bubbles.

During vacuuming it is still 9 psi, and the filter basket is still almost only half full. during vacuuming, the return seems to be blowing out a lot of bubbles, some big "gulpy" ones.

i'm still stumped. Where is the air coming from, and why is the pump basket only 1/2 full during vacuuming??

Frank D.

After thinking about this a bit, I am convinced I have a sucking air problem somewhere. I do hear a gurgling/sucking noise just under the skimmer basket, (I JUST found).

Also, I hear a gurgling, air trapped, "jumping pebbles" sound in the multiport valve, like trapped air. Looking through the clear top where the pump basket is, there is always not a bunch of swirling bubbles on the top that are trapped in the dome of the top.

None of this was like this in past years. Ironically, I was more careful this year with connections, replacing teflon tape, etc.

I will replace the vacuum hose, and recheck ALL connections until I solve this thing.

The pump basket drain is ok, and I'm pretty sure the o rings are ok and the pump basket clear lid is good and tight and the o-ring lubed. I'm thinking the air leak is just under the skimmer basket, or a pinhole in the vacuum hose.....

I just do not know why the problem is much more evident when vacuuming, and hardly there when skimming.....unless it IS the vacuum hose......

I'll solve this thing even if I have to JB Weld everything...!

Frank D.

Frank,
You're on the right track. Leak has to be on the suction side. I also think you may have nailed it by suspecting the skimmer hose. Remember that all it takes is a tiny crack at a rib in the hose to leak enough air to mess things up. The crack could be so small water may not leak out when the pump isn't running. If you bend and stress the hose a little while it's pumping you should be able to find the crack pretty easily. As for the problem being more obvious while vacuuming, simple, you're vacuum cleaner is restricting suction side flow and you're pulling a higher vacuum (negative pressure) as indicated by the 9 psi reading on the pressure side. More restriction on the suction side = lower pressure on the pressure side.
Al

Well, I just got home from work, so I went out to play.

I tightened the suction side in a few places, and I took off the big plastic nipple that screwed into the bottom of the skimmer basket. I first had to figure out how to stop up the hole so I would not lose 6" of water....I used a ball.

I retaped the nipple and screwed it back in, then retightened all hoses.

The bubbles went totally away from both the return jet water flow and the clear top of the pump basket strainer. The psi when skimming went up to 15 psi.

I next tried vacuuming. The vacuum is much stronger. The psi dropped only to 12.5-13 and only the tiniest bubbles are seen in the clear pump skimmer basket. No more big gulps out of the return!!

I still have some bubble noise in the multi-port, but all in all I think things are much better. I did find another drain plug underneath the pump I never knew existed, and I tightened that up too.

I think next year I'll take everything apart and use rectorseal on everything.

Frank D.

Another successful story with a happy ending. Good work.
Al