Air in the system

[Phillbo]

Hello all and welcome to another season.

My pump runs for about 6 hours in the morning and then shuts off. When it first kicks on in the morning there is a lot of air in the system creating big bubbles of air from the returns in the pool. It bubbles for about 10 seconds and then clears up.

Items i have done to try to eliminate the large amount of air:
-- Replaced the pressure relief valve on top of the filter
-- Cleaned and lube o-ring on chlorine generator and the pump basket
-- Replaced the 0-rings in the back wash valve.

I'm assuming I have a leak somewhere but am at a loss on where else to look. I don't see any water on the ground that would indicate a leak. It appears to me that the filter is where the issue is as the pump basket and chlorine generator housing are full in the morning.

One thing to note is that this began just after a complete tear down and cleaning of the filter grids (DE filter). If the o-ring on the filter was not seating I would assume i would see water running down the filter as air was being introduced.

Any advice is greatly appreciated.

[Anonymous [GDPR] European in the UK]

I think you are on the right track, the first place I look is the lid of the pump pre filter. the O rings go hard and square after a while so no amount of grease will fix it, better for a replacement. I have just replaced 6 O rings on my customer's pool as they were in poor shape.
Good luck and let us know.

[mas985]

Since the air leak appears after the pump is shut off, the air leak could be anywhere including the filter.


One thing to note is that this began just after a complete tear down and cleaning of the filter grids (DE filter). If the o-ring on the filter was not seating I would assume i would see water running down the filter as air was being introduced. Not necessarily. Sometimes leaks can be one way only depending on the geometry. This is especially true with o-rings because the high pressure when the pump is on will tend to seal the o-ring.

[swimdaddy]

If air is getting into the system with the pump off, wouldn't that have to occur above the water line? If there was a leak below the water line, than the pressure of the water would push water out, not air in, right? I know I am probably wrong, just trying to stimulate further conversation.

[Phillbo]

I found the culprit. It was the backwash valve. It was cracked and allowing air to enter the system once the pump shut off (found this by accident when i had to replace the valve due to the handle snapping off). New valve and o rings and there is no longer air in the system when it starts up in the morning.