Air in return water

[Kwikee]

I've got what may be an issue with air bubbles in the return water jets. When the filter first starts, there is a large amount of air in the lines which reduces after a few seconds but a steady stream of small bubbles persists for as long as the filter is running. When the pump stops, I can't hear air/suction noises at the filter/valve/pump yet when it next runs after a few hours, the air is there.
Obviously there's a leak somewhere, but is there a usual culprit? I'm new to this, the pool came with the house we bought and have been here since just before Christmas.
I'm not particularly concerned abut it, but I've read that the pH can be raised because of it which appears to be the case here.
Any advice before I call the local pool shop to come and have a look?

 

[JohnT]

The first thing to check is the pump strainer basket. Are there any air bubbles there?

 

[Kwikee]

There looks to be bubbles passing through it, and you can hear the water through the pipes has the same crackling sound as the jets. The strainer basket is also not completely full of water, there seems to be about an inch of air inside the clear lid, and it is screwed down tightly.

 

[duraleigh]

The air leak is somewhere between the pump and the skimmer(s). YOu have to be pretty methodical and eliminate every valve, joint, etc as you go along.

Start with the skimmer...is the water in the pool deep enough that no air is being sucked in the skimmer? If so, move to the next visible (above ground) spot that MIGHT be sucking air and absolutely make sure it is airtight.

Even if the pump basket lid is on tight, air can still get in if the O-ring is not seated properly or damaged.

 

[Kwikee]

Thanks for the replies. I'll give it a good check tomorrow and report back. I did notice tonight, though, that there are a couple of valves in the ground with a push handle on them to open and close, one is obviously in the line from the skimmer, the other I have no idea. It changes nothing when opened or closed while the pump is running. Could be in the waste line? Anyway, I'll get back to you!

 

[Kwikee]

Resurrecting this old thread, I ended up checking everything I could to no avail and just ran with the bubbles. I happened to be near the filter the other day just after it had stopped running and noticed I could hear an air sucking noise from it. I thought it was the little glass backwash bulb, but it seems to be coming from the valve. The filter is an older StaRite side valve. When I moved the lever a bit or pulled up on it a bit, the noise changed so I think this might be the culprit. I think I can get the gasket kit for it, do you think this might be the source of the problems?

 

[duraleigh]

do you think this might be the source of the problems?

No. Air is sucked into your system only on the suction side. The multiport is on the pressure side of your system and, pump running, cannot suck in air.

Your air leak is still somewhere between the skimmer(s) and the pump.

 

[Kwikee]

OK. I will most likely be moving the whole system to a different location in the yard so I am going to re-plumb from the skimmer anyway. Would I be right to assume that the plumbing will be run together in a single trench, so once I find one pipe I have found them all? There looks to be only the line from the skimmer to the pump and the return lines to the jets, plus there must be a line to the drain for backwashing.

 

[duraleigh]

Would I be right to assume that the plumbing will be run together in a single trench

Very likely.

 

[mas985]

There is a possibility that it could be the backwash valve. Since the filter is above the water line, when the pump is off, there is a slight vacuum in the filter and the backwash valve can sometime leak air into the filter. I would check and lube the o-rings in the valve.

 

[Kwikee]

Well I have finally found the problem, and pretty much by accident! I am about to move my pump station and will need to re-run my plumbing from the various points to the pump. I have broken out the concrete behind the skimmer first and found a cavity about 1 cu.ft around the back of the skimmer, exposing part of one pipe. It turns out the 90* bend arrowed has a leak, and without concrete above it, you could hear the suction of air!
[attachment=0:ma5k6xm6]3.9.13 skimmer pipe.jpg[/attachment:ma5k6xm6]
There's a bit of water in there, probably due to both a small leak from this bend, and also seepage from the base material laid in the trench. Glad I found it, but now where does that pipe go? It's pointing 180* away from where I thought it should go...