Solar panel - LOTS of bubbles in the return jets

[dayhiker]

Late last summer I started getting some bubbles in the return jets. So far this year, there are lots and lots of bubbles. I can't imagine where I'd be sucking air in. To suck in air, wouldn't you also have to have a leak? The only place I see any type of leak is a slight smear of wate down the face of the catridge filter where the top and bottom is bolted together. I put more CYA in the pool Sat, so I'll wait a week before taking the filter apart for spring cleaning. Any other thoughts or solutions? Thanks.

 

[dmanb2b]

big bubbles or fine? It could just be the SWG kicking off

 

[dayhiker]

big bubbles or fine? It could just be the SWG kicking off

I'd say a step above fine. This is pretty well continuous while the solar is running. If I turn off hte solar, the bubbles go away.

 

[257WbyMag]

Couldn't that just be CO2 outgassing from the water in the solar system? Lots of little bubbles, right?

 

[JohnT]

Sometimes you'll get bubbles in the returns with solar that I believe is caused by the water falling down the outlet pipe of the solar faster than it goes in. I don't know for sure if it is outgassing during the pressure drop, outgassing cause by turbulent flow through the panels, or something similar to cavitation.

Sometimes you can stop it by reducing the size of one or more eyeball fittings and/or adjusting your bypass or 3-way valve to send more water to the solar.

Seems like you see this most often on pools that have really low flow resistance to the returns.

You might try rotating an eyeball or two to 90 degrees or playing with your bypass to see if it clears it up.

 

[dayhiker]

Sometimes you'll get bubbles in the returns with solar that I believe is caused by the water falling down the outlet pipe of the solar faster than it goes in. I don't know for sure if it is outgassing during the pressure drop, outgassing cause by turbulent flow through the panels, or something similar to cavitation.

Sometimes you can stop it by reducing the size of one or more eyeball fittings and/or adjusting your bypass or 3-way valve to send more water to the solar.

Seems like you see this most often on pools that have really low flow resistance to the returns.

You might try rotating an eyeball or two to 90 degrees or playing with your bypass to see if it clears it up.

I totally unscrewed the eyeball to see if the bubbles were still there and they were. So you're saying go with a smaller eyeball so that the pressure will increase? I should also note, that the return nearest the pump is the only one to do this. My concern about this, is that won't those tiny bubbles also cause a greater pH rise due to aeration? I add enough acid as it is imo. Also, with iron in the water, this creates even more pH concerns.

On the bypass issue, when I turn solar on, I turn it on all the way, so I can't send more water to the solar than I already am.

 

[mas985]

If air were to enter the solar system, it is more likely to be from the vacuum release valve. Cavitation bubbles collapse soon after they are formed, so you would not be able to see them. Not only that but a VR would open well before cavitaion or outgassing of any type could occur.

Usually the reason that air enters the vacuum release valve is because the water pressure drops below 0 PSI at the valve. This is sometimes caused by a very high solar install coupled with a low head pump and dirty filter. However, in your case the pump is fairly high head and should easily provide the pressure to keep the VR closed. What is the filter pressure when the solar is running and how high are the panels installed?

You mentioned that the bubbles were fine which would be typical for a SWG. Are you sure they are not caused by the SWG? Do they go away when the SWG is shut off?

 

[JohnT]

First, try rotating an eyeball crossways to the flow. Costs nothing and only takes a minute to try. Probably better to use one other than the closest so you can observe the effect. You should see some pressure rise. Increasing the pressure between the pool and filter is what you want to try.

 

[dayhiker]

If air were to enter the solar system, it is more likely to be from the vacuum release valve. Cavitation bubbles collapse soon after they are formed, so you would not be able to see them. Not only that but a VR would open well before cavitaion or outgassing of any type could occur.

Usually the reason that air enters the vacuum release valve is because the water pressure drops below 0 PSI at the valve. This is sometimes caused by a very high solar install coupled with a low head pump and dirty filter. However, in your case the pump is fairly high head and should easily provide the pressure to keep the VR closed. What is the filter pressure when the solar is running and how high are the panels installed?

You mentioned that the bubbles were fine which would be typical for a SWG. Are you sure they are not caused by the SWG? Do they go away when the SWG is shut off?

They are only present when the solar is running. I'll try turning the swg to 0 and see what happens.

I'll check the pressure too. I think it's at the edge of the clean/dirty reading. I believe it's 20, but will need to check. It is definetely time to clean the filter but will wait a week to let the cya cycle through.

The filter might be a good explanation for why this is a new issue.

 

[dayhiker]

First, try rotating an eyeball crossways to the flow. Costs nothing and only takes a minute to try. Probably better to use one other than the closest so you can observe the effect. You should see some pressure rise. Increasing the pressure between the pool and filter is what you want to try.

I was in the pool for a bit yesterday. I rotated that eye many different ways and watched with a mask on. No change.

 

[JohnT]

First, try rotating an eyeball crossways to the flow. Costs nothing and only takes a minute to try. Probably better to use one other than the closest so you can observe the effect. You should see some pressure rise. Increasing the pressure between the pool and filter is what you want to try.

I was in the pool for a bit yesterday. I rotated that eye many different ways and watched with a mask on. No change.

I'd try putting a winterizing plug in one return just to see what makes the bubbles go away to narrow it down.

 

[dayhiker]

First, try rotating an eyeball crossways to the flow. Costs nothing and only takes a minute to try. Probably better to use one other than the closest so you can observe the effect. You should see some pressure rise. Increasing the pressure between the pool and filter is what you want to try.

I was in the pool for a bit yesterday. I rotated that eye many different ways and watched with a mask on. No change.

I'd try putting a winterizing plug in one return just to see what makes the bubbles go away to narrow it down.

I don't have one of those. Would putting the heel of my hand over it do the same thing? My wife could check the other returns.

 

[JohnT]

I don't have one of those. Would putting the heel of my hand over it do the same thing? My wife could check the other returns.

I'd expect so. Anything to raise the pressure a few PSI.

 

[dayhiker]

It was a quick trip home and I didn't get to do the pressure test.

1. The bubbles were not there.
2. The solar cell said, "Cell on, cell reversing"
3. I did iron treatment about 3 weeks ago. My FC was 0 today. The SWG is running about 4 hours per day at 50%. I upped it and put about 1qt of bleach in. 1 week ago it hit 0, I put a whole 182 jug in to get it to FC=3 and had a green pool from a reaction within about 1 hr.
4. pH is still holding at 7.2 three+ weeks after citric acid.
5. Filter pressure = 20 psi.
6. I'd say the elevation difference from pump to relief valve is in the neighborhood of 25'.

I think that covers all the info I either didn't have or didn't answer.


The fact that the bubbles weren't there almost does make it sound like a swg thing.....wonder if the fc continuing to bottom is solely from citric or partly from cell function? My cya is around 50-60 and should be climbing to 70 after putting 2#'s in the other day. I'm waiting until this weekend to check it. Alkalinity is around 70 while I'm listing chemical levels.

 

[mas985]

Did you get the SWG running and did the bubbles reappear? Sounds like you could be fighting an algae bloom.

If it isn't the SWG, I bet the problem goes away with a filter cleaning. The 20 PSI is with solar? What is it normally when the filter is clean?

What I think is happening is fairly typical of solar with a dirty filter. As the filter gets dirty, the pressure drop across the filter rises reducing the flow rate in the entire plumbing system. This drops the pressure at the top of the panels. If that drops below 0 PSI, the vacuum release opens sucking in a little air. If you plug a return, the pressure rises enough to close the vacuum release. You are right on the edge for pressure and need to clean the filter.

 

[dayhiker]

Did you get the SWG running and did the bubbles reappear? Sounds like you could be fighting an algae bloom.

If it isn't the SWG, I bet the problem goes away with a filter cleaning. The 20 PSI is with solar? What is it normally when the filter is clean?

What I think is happening is fairly typical of solar with a dirty filter. As the filter gets dirty, the pressure drop across the filter rises reducing the flow rate in the entire plumbing system. This drops the pressure at the top of the panels. If that drops below 0 PSI, the vacuum release opens sucking in a little air. If you plug a return, the pressure rises enough to close the vacuum release. You are right on the edge for pressure and need to clean the filter.

I upped the swg %, but nothing changed. I only had about 10 minutes at home. I'll play with it more this evening. Are you saying algae could have something to do with it?

I'll add some more bleach when I get home, and then more in the morning. I got a barely visible pink hue on the CC. Calling it 0.5 would be pretty generous.

I put the extra CYA in on Sat. I'll clean the filter Sat and see what happens?

Normal filter pressure, hmmm, maybe 13.

 

[mas985]

Yes, definitely the algae would plug up the filter which in turn would then cause the low pressure at the VR allowing air to enter the system. Going from 13 PSI to 20 PSI in the filter is a 50% increase which is very significant. With a 24k pool and a 340 sq-ft cartridge, it really shouldn't plug up that quickly unless there was a lot of algae.

Also, you have fairly low pressure for a system with solar. Normally a 1.5 HP pump would have pressure beyond 20 PSI without solar and much higher with solar. So that compounds the problem. One of these situations may apply to you:

1) Low return head loss usually because large pipes are used on the return side relative to the suction side.
2) High suction head loss usually because small pipes are used and/or a partial blockage or restriction.
3) Pump impeller clog.

I would have expected a lot higher filter pressure than what you are seeing. Has the filter pressure always been that low? What is the clean filter pressure without solar?

 

[dayhiker]

Yes, definitely the algae would plug up the filter which in turn would then cause the low pressure at the VR allowing air to enter the system. Going from 13 PSI to 20 PSI in the filter is a 50% increase which is very significant. With a 24k pool and a 340 sq-ft cartridge, it really shouldn't plug up that quickly unless there was a lot of algae.

Also, you have fairly low pressure for a system with solar. Normally a 1.5 HP pump would have pressure beyond 20 PSI without solar and much higher with solar. So that compounds the problem. One of these situations may apply to you:

1) Low return head loss usually because large pipes are used on the return side relative to the suction side.
2) High suction head loss usually because small pipes are used and/or a partial blockage or restriction.
3) Pump impeller clog.

I would have expected a lot higher filter pressure than what you are seeing. Has the filter pressure always been that low? What is the clean filter pressure without solar?

This pressure increase hasn't been sudden. I'm way past due to clean the filter. It was probably mid summer the last time I did it.

Yes, the pressure has always been low.

I'll turn the solar off this evening and compare pressures and report back.

 

[dayhiker]

Pressure: 20psi with solar going, 14psi without it.

 

[mas985]

And that is with a dirty filter, correct? That is really low for an uprated 1.5 HP pump. Can you describe your plumbing to me? Lengths and number of runs pool to pad, pipe size?