a tiny bit of air in the DE filter

Diver · Jun 13, 2011

It seems that I always have a very tiny bit of air in the filter. I can turn the bleed valve maybe a 1/8th of a turn and let the air out and it takes a second or two for water to start coming out. And then the next day the air is there again. The filter is making some subtle noise (cavitation?) and it gets a bit better after I let the air out. Nothing significant or excessive, a tiny bit of air and some subtle noise.

Is this normal or do I have a small vacuum leak? Can the water outgas if there is some pressure drop somewhere in the filter? No bubbles in the returns.

Bama Rambler · Jun 13, 2011

You have an air leak somewhere in the suction side of the pump.

The most common places are the skimmer creating a vortex, the skimmer weir sticking, the pump strainer basket lid & the pump strainer drain(s).

Diver · Jun 14, 2011

Dave,

My water level is high, so i think skimmer is probably not a problem. i will make sure that the pump lid and drain are tight and retest. there is not a bubble in the basket when pump is running.

on the weekend i want to bleed the air right after pump is started and check at the end of the run. if there is no air, it would mean that the air gets to filter when the pump is off.

it's very small amount of air, so i'm not overly concerned.

Diver · Jun 15, 2011

i did my experiment and it appears that the air gets to the filter when the pump is off. i bled the air today after pump started and there was no air 7 hours later. does that mean that i have an air leak in the filter?

i have a tiny water leak on the pressure side of the pump - couple of oz per hour or so. can that lead to the air in the filter when pump if off?

Bama Rambler · Jun 15, 2011

A leak in the pressure side cen translate to an air leak when tthe pump is off.

Diver · Jun 22, 2011

i start to suspect skimmer weir now - yesterday i found the flow in the skimmer being weird, i moved the weir around and the flow went back to normal. so it sounds like it might be the cause of the air in the filter.

i'm going to shut off skimmer intake for a day to see if it helps (i have a cover on, so no skimming for a day is not a big deal). and i will take a look to see if there is something i can do to make sure the weir is free to move

how bad is the air buildup in the filter?

Bama Rambler · Jun 22, 2011

Most of the time it will self purge at least partially so it's not a huge deal. It will make the pump lose prime in some instances.

Diver · Jun 27, 2011

i think i figured out how the air gets to the filter. it's not when the pump is off how i originally though. and it's not when pump is running either - it's right on the pump start up.

the pump stays fully primed in off hours. but right on start up some air gets into the pump basket, i see some minimal turbulence and then it goes all clear in about 5 seconds. i assume all the air then goes to the filter and stays there.

i suspect that the lid lets some air in when the vacuum jumps on start up. it seems to be sealed nicely and has o-ring has plenty of silicon on it. the o-ring has some "bite" deformation from the lid which might be the culprit, but i couldn't fix it.

since i tend to the pool daily and can bleed the air it's more of annoyance. i guess i will have to live with it