Air leak...any ideas?

[mculik5]

Just opened our pool for the summer. Water is already looking great, and I successfully installed a SWG, but I'm struggling with an apparent air leak.

Here's what's happening:

- Turn the pump on. System runs at ~12 PSI and ~60 GPM.
- Over the course of two hours, pressure climbs to ~20 PSI and flow drops to ~45 GPM.
- If, after two hours, I turn the pump off for a long time, the above cycle repeats. Alternatively, if I turn the pump off for a short time, it's at ~20 PSI/~45 GPM when I turn it back on.

Other things I've noticed:

- If I suck from the skimmer only, I get a nickel size bubble vortex in the pump.
- If I suck from the skimmer AND sidewall, I have almost no bubbles in the pump (maybe a few BB-sized ones).
- The port at the bottom of the skimmer is solidly under water - no slurping air or anything like that.

What I've done:

- Replaced all O-rings - pump lid, pump drain plugs, and all three suction-side unions.
- Lubed all O-rings.
- Applied Real-Tuff thread sealant to all three suction-side unions.

What I'm wondering:

- Any ideas?
- I always thought unions should be as tight as you can get them by hand, which mine are. Should I just crank on them with a strap wrench and see if that helps?
- Can I read anything into the fact that I have relatively few bubbles in the pump? I'm thinking any air entering from the unions before the pump would collect at the top of the strainer, whereas air entering from the drain plugs would be pushed to the top of the filter...?
- How, exactly, does an air bubble in the filter block flow? Why doesn't the system just burp such bubbles out?

Thanks!

 

[Jimrahbe]

5,

What you describe is exactly what happens when you have algae, even when you can't see it...

If this were my pool, I would run an Overnight Chlorine Loss Test... OCLT..... Overnight Chlorine Loss Test

I believe that you have a chemical issue and not a mechanical issue.

Thanks,

Jim R.

 

[mculik5]

What you describe is exactly what happens when you have algae, even when you can't see it...

I don't doubt what you're saying, but can you describe how algae causes this behavior?

The water looks good (not to say there isn't algae), and I don't have the ladder or anything else in the pool where algae typically hides. I also shocked the pool to a high FC value on Sunday (haven't checked the water since if I'm honest). The water is only 66 (in NJ, no heater), and all of the equipment was drained for the winter. I've only been flowing water through the filter since Sunday, and only for a few hours a day because of this issue (can't leave it on overnight or while I'm at work or it'll keep going to 30 PSI and almost no flow).

I'll give the OCLT a shot, but am curious how algae causes this behavior.

Thanks.

 

[duraleigh]

but am curious how algae causes this behavior.

The algae is being drawn into your filter, clogging it and causing your psi to increase and your flow to stop.

SLAM your pool and the filter will no longer clog and your psi will stay where it started and your flow will stay at 60.

You must kill the algae with chlorine and then remove the dead algae from your system by cleaning the filter

 

[mculik5]

The algae is being drawn into your filter, clogging it and causing your psi to increase and your flow to stop.

This makes perfect sense to me...except, why does the problem seemingly reset if I turn the pump off for awhile? If algae is clogs the filter, the filter should stay clogged until I backwash, no? As I said, if I turn the pump off for several hours and then turn it back on, it runs at 12 PSI/60 GPM for a period of time. This (12PSI/60 GPM starting point) has been consistent since Sunday.

Not arguing - just wondering. Thanks.

 

[Jimrahbe]

5,

Think of this like going to the doctor for a sore arm.. The doctor takes an x-ray to rule out if the arm is broken or not.. He might even have a good idea that the arm is not broken, but he takes an x-ray just to make sure.. Doing an OCLT is just to rule out the obvious.. It just makes sense, when the problem is odd, to try and rule out what is the cause in 95% of the cases.

Or, when the wife goes missing... it's the husband, it is always the husband...

Jim R.

 

[duraleigh]

If algae is clogs the filter, the filter should stay clogged until I backwash, no?

No. The clogged debris loosens when you suddenly drop pressure by turning off the pump. This breaks up the blockage enough that the water can then flow freely until the clog material "resettles" onto your sand bed. That is a very, very common pattern.

 

[mculik5]

Thanks for the help! I completely forgot to do the OCLT last night/this morning, but I did backwash yesterday morning and the system ran at 12-13 PSI and ~60 GPM all day. As you suspected, looks like the filter quickly clogged cleaning out all the gunk in the water from the winter.

Water was perfect this morning.