SWG - Tiny Cloudy Bubbles coming from jets

[Shieldsfx]

I have a goldline Aqua Right SWG, about 2 years old. At times, I notice there is a very obvious "cloudy or milky flow" coming out of the pool jets. At first, I thought it was the DE, but it is not. It only happens when the SWG is on. The milky flow dissipates after it integrates with the pool water (after 3 minutes or so). I noticed the higher the SWG %, the darker the milky flow. It's a very obvious and causes people not to want to swim.

After much research, I believe it is tiny hydrogen bubbles produced by the SWG (goldline talks about this in their spec), and I have notived they are much more obvious at low pump flow rates (I have a variable speed pump). Does anyone have specific knowledge of this area to advise me?

 

[subslug]

I've seen this on some of our pools with SWGs and I assumed it's just the chlorine gas being injected into the pool.
I'm sure there's a much more technical reason for it but basically it's just your SWG doing it's job, unless it's clouding you pool up.
Then it might be an air leak or something else.

I dipped by test cell with cap on in front of the jet in a pool once just to see, pulled the cap off under water to capture the flow from the jets input and tested the chlorine, WOW...it's pretty off the chart at that point in the pool.

Thats why they say to test away from the jets.

 

[JasonLion]

Welcome to TFP!

Yes, it is very likely to be hydrogen bubbles. All SWGs produce some excess hydrogen gas. However, for most people, they are not nearly as obvious as what you describe. I have to look really closely to see them in my pool.

 

[Shieldsfx]

Thanks for the responses so far. I'm sort of posting an update to my orginal posting, as I have found several threads from "Chem Geek", who seems to have shed more light on this issue (I hope he checks my posting and responds, because he seems to be the expert in these complex topics??)

It seems SWG may produce TWO items of note out of the pool jets: 1) hydrogen bubbles (as noted in several threads/specs on this topic), and 2) Chlorine gas.

#1, hydrogen bubbles, can be seen from the jets, but are usually very tiny and more apparant at night, in the shine of the pool light. They are clear tiny bubbles and usually dissapate without notice.
#2, Chlorine gas. After reading threads from CHEM GEEK, I believe it is what produces the milky white spew out of my jets. CHEM GEEK mentions in another unrelated thread that if the pipes are of short distance from the SWG, it will produce a cloudy effect, as the chlorine gas does not have sufficient time to mix with the water. This is indeed the case for me, as my SWG is about 15 feet from the pool jets. For my Spa jets, which are 25-30 feet, I never see the effect of either hydrogen bubbles OR Chlorine gas, as it seems they get a good chance to mix with the water before getting to the spa. Also, I have a variable speed pump and I noticed the gas is much more obvious at low flows than high flow rates.

BTW, the manufacturer (Hayward/Goldline) responded to my same question and they stated that "There is no byproduct of the chlorination process which creates such an effect on a normal basis. The only time we hear of this is if people have used algaecide recently or if there is some other chemical issue occuring in their pool..." I would word this response differentlly, by saying "The primary byproducts of the SWG is hydrogen and chlorine gas, both of which may be seen at times under certain circumstances, such as low flow rates, distance of pipes from SWG, and chemical balance in the pool..."

I look forward to any confirmation of my research above.

 

[chem geek]

We all work together on figuring things out and none of us has an exclusive on a good idea, but thanks for the compliment anyway.

I don't recall ever saying that the chlorine gas would make the water cloudy. I was writing about the possibility that the chlorine gas generated by the SWG may not fully dissolve so could then outgas and that would explain a rise in pH that would not be prevented by lowering the TA.

Having the SWG close to the return jets would make it more likely for chlorine gas bubbles to persist. Having a slower flow rate would tend to have the hydrogen gas bubbles be larger (it's unclear as to whether the chlorine gas bubbles would be larger because they also have more time to dissolve).

Regardless of whether the bubbles are only hydrogen gas or are a combination of hydrogen and chlorine gasses, such bubbles could make the water look a little milky as you can see with a carbonated beverage and vigorous stirring.

The difference with your pool and spa may be not only the distance, but also the water temperature. The rate of dissolving of the bubbles is likely faster at higher temperature.

I'm confused by your statement about it taking about 3 minutes or so for the milky flow to integrate with the pool water. Do you mean that after 3 minutes of the SWG being on that it is less milky-looking at the returns? It shouldn't take 3 minutes for the water to flow from the returns into the bulk pool water so I don't know what you mean.

Richard

 

[Strannik]

don't think this is a problem here, but we had a similar case in one of our commercial clients' pool.
what it turned out to be that it was a painted pool and was well overdue for a repaint
for some reason when chlorinator ran that paint from the sides and the bottom was ending up as a cloudy water from jets

took a while to figure out that one, i don't even know how many water tests the guys who handled it had to do

in your case, i'd say it's a chlorine gas

 

[Shieldsfx]

After reviewing the feedback I have performed more tests, as shown below.

First to answer Chem Geeks question: “I'm confused by your statement about it taking about 3 minutes or so for the milky flow to integrate with the pool water”. What I mean is that the milky substance dissipates into the pool after a short time period; in other words, after it moves about 5 feet into the pool, the jet water becomes clear, not milky anymore.

After your point about “Temperature”, I performed the following tests:
1. Low Flow (30 GPM) pump with no SWG and no Heater: no milky substance
2. Low Flow pump with 100% SWG: faint milky substance.
3. Low Flow pump, 100 SWG AND Heater: much darker milky substance.
4. Same as #3, but 50% SWG: milky substance gets lighter
5. Same as #3, but double pump flow speed (60GPM): very faint to almost no milky substance
6. Note that all tests showed milky substance on pool jets but none detected on spa jets 20 feet further (same pump drives pool/spa).

I have attached a couple photos of the jets spewing the milky substance. Clearly the heater is making the biggest difference to the color of the jet stream.

Therefore, it is clear these are the factors that will contribute to this condition:
1. Low Flow Pump
2. SWG on
3. Heater on
4. Distance of SWG to pool jets close.

The question now is: is it hydrogen or Chlorine? I think a mix of both but mostly Chlorine?[attachment=0:ejtlj92f]IMG_1565.jpg[/attachment:ejtlj92f]

 

[JasonLion]

It seems possible to me that you are seeing calcium clouding. Could you post a full set of water test results? We should be able to confirm or rule out calcium given a full set of water test results.

 

[chem geek]

(I posted while Jason posted...his calcium idea should be checked out as well since higher temperatures tend to scale more so could cloud the water from calcium carbonate and the high pH from one of the two SWG plates could also be forming calcium carbonate)

Mmmmm. That's weird. Well, the heater comes before the SWG so when the water is hotter that is apparently making this bubble action be far more visible and darker. A lower quantity of gas can dissolve in hotter water so perhaps the hydrogen gas is more saturated in the water at the higher temperature so more of it stays undissolved causing the water to have a more intense milky appearance. The chlorine gas, on the other hand, should dissolve more quickly (faster reaction rates) and the water won't be saturated with chlorine since it gets converted to hypochlorous acid. If this is true, then the primary source of your milky water is probably the hydrogen gas bubbles and not the chlorine bubbles.

On the other hand, this doesn't explain why you don't see this in the spa unless the hydrogen gas itself is able to dissolve into the water, but I would think the water would get saturated pretty quickly. The distance effect is more likely due to chlorine gas since it will dissolve but takes time (distance in a water flow) to do so. It is interesting that a difference in distance of 20 feet is making such a huge effect. I wonder if the nature of the pool vs. spa nozzles and their number and flow rates through those returns isn't another factor here.

Richard

 

[New2Me]

I don't think that the bubbles will dissolve, they just float up and away. I used a 30' and a 4' outlet hose with my SWG and had bubbles with both. I looked at it as a sign that the electrolysis was working(or is that for hair removal?)

It's a very obvious and causes people not to want to swim.

I don't run the SWG when people are in the pool, even though it is plugged into a GFCI outlet. After all, it IS just an electric cord with metal plates in your pool water(electrolyte)!

 

[Shieldsfx]

As an update, here's my pool's chem balance:

FCL=7.1
TCL=7.5
PH=7.6
ALK=80
CH=190
CYA=70
Salt=2900
Temp=74
PebbleTec Gunite Pool

Jason, if it were Calcium Carbonate would it dissipate so quickly after leaving the jet? wouldn't the pool be cloudy? Other than the this condition, pool clarity is very good.

Richard, I believe you are right about the spa flow/number of jets being a factor in this saga. Again they are 20-25 feet from SWG but there are 8 jets in the SPA. Remember, the pool Jets are about 10-15 feet from SWG and only two jets.

Fran

 

[JasonLion]

If the CSI in the pool is negative then small calcium particles will dissolve. For the calcium particles to form in the first place CSI would need to be sharply higher in the SWG. Both are possible, and the difference would increase in the situations you describe as worse.

 

[spishex]

Mind posting a pic of the equipment set up as well when you get a chance?

 

[JasonLion]

I did some calculating and the calcium theory doesn't look plausible. There would have to be too dramatic a CSI increase in cell and I can't think of any way it could be that large. If you're TA had been lower and CSI higher it could have been calcium, but with your actual numbers it doesn't seem plausible.

 

[Shieldsfx]

See attached pool equipment configuration. Note that I have a swim jet, hence the extra large pipes/pump. Main pump is a Inteliflo Variable Speed.

 

[chem geek]

Richard, I believe you are right about the spa flow/number of jets being a factor in this saga. Again they are 20-25 feet from SWG but there are 8 jets in the SPA. Remember, the pool Jets are about 10-15 feet from SWG and only two jets.

Fran,

So the problem occurs the worst with the SWG on, worse with the heater also on, and through the pool's 2 jets at 30 GPM so 15 GPM per jet. The problem is far less at faster speed, 60 GPM so 30 GPM per jet. The problem does not show up at the spa at 60 GPM with 8 jets which would be 7.5 GPM per jet (you never said if you tried running the spa at low-speed, which isn't something you'd normally do).

So if the split in plumbing for the jets were closer to the SWG, and if the individual pipes to the jets were 1.5" (they may be 2" at the pump, but are likely smaller when split to each jet), then the following shows the velocity in the pipe, distances, and calculated time in the pipe:

POOL @ 60 GPM: 30 GPM per jet, 4.73 feet/second, 10-15 feet, 2.1 to 3.2 seconds -- result: very faint to no milky substance
POOL @ 30 GPM: 15 GPM per jet, 2.36 feet/second, 10-15 feet, 4.2 to 6.4 seconds -- result: faint to darker (with heater) milky substance
SPA @ 60 GPM: 7.5 GPM per jet, 1.18 feet/second, 20-25 feet, 16.9 to 21.1 seconds -- result: no milky substance
SPA @ 30 GPM: 3.75 GPM per jet, 0.59 feet/second, 20-25 feet, 33.8 to 41.3 seconds -- result: not tested

So it looks like the slower flow rate through the SWG may cause larger more visible bubbles to form. These don't spend very long in the pipe when going to the pool so show up more, while in the spa there is enough time for these bubbles to dissolve or otherwise disperse to not look milky. Also, larger bubbles have a lower surface area to volume ratio so dissolve their contents more slowly than smaller bubbles.

We still don't know if the bubbles are hydrogen gas or chlorine, but I suspect they are chlorine since longer time in the pipe has them disappear (by dissolving into the water). The hydrogen gas bubbles probably don't dissolve much since the water should get saturated with hydrogen gas fairly quickly. Chlorine gas is pale green, but your milky stream looks off-white without a tint, but chlorine gas in many bubbles in water might not look green.

One way to tell if there is undissolved chlorine gas coming out of the jets is to dynamically measure the pH of that jet stream in the case with slow flow in the pool with lots of bubbles compared to the spa. You can't just do a standard sample collection for this since the chlorine gas would have time to dissolve before you could measure the pH -- it needs to be something more dynamic such as a pH probe or perhaps a pH test strip viewed in the water. The pH of the water should be higher if there is undissolved chlorine gas.

Richard

 

[Shieldsfx]

Richard,

I had already realized that there was one test I did not perform, but you caught it in your last note. So, I ran the SPA on low flow, SWG 100% and heater on. As you said, it is not typical to run the SPA on low flow so I wouldn't have seen this in earlier tests.

In fact, the tiny bubbles/milky flow were also present in the SPA test! All eight jets showed the bubbles, but not as clearly as in the pool, since the flow was spread across all eight jets. See pictures. You’ll note I have taken a second picture of the pool and SPA together noting that the whole SPA became “cloudy” with these bubbles. To confirm my theory that these were in fact bubbles, I turned off the SWG in the SPA and the water cleared up within minutes (and very tiny bubbles could be seen breaking at the surface of the water).

For the last test you recommended, I have a dynamic PH tester, and I tested the surrounding water at 7.84 and when placed into the “milky jet”, PH rose to 7.89.

 

[chem geek]

OK, so we've now got:

POOL @ 60 GPM: 30 GPM per jet, 4.73 feet/second, 10-15 feet, 2.1 to 3.2 seconds -- result: very faint to no milky substance
POOL @ 30 GPM: 15 GPM per jet, 2.36 feet/second, 10-15 feet, 4.2 to 6.4 seconds -- result: faint to darker (with heater) milky substance
SPA @ 60 GPM: 7.5 GPM per jet, 1.18 feet/second, 20-25 feet, 16.9 to 21.1 seconds -- result: no milky substance
SPA @ 30 GPM: 3.75 GPM per jet, 0.59 feet/second, 20-25 feet, 33.8 to 41.3 seconds -- result: milky substance

So my initial thought of the time spent in the pipe helping the situation isn't really a big factor, though may make a small difference. The main factor is the flow rate through the cell with slower flow resulting in a much greater milky effect. When combined with the basically similar pH measurement you saw, this means to me that the chlorine gas is probably mostly dissolving quickly, so that means the milky appearance is most likely hydrogen gas bubbles. I'm not sure why the heater makes the problem worse except that the gasses saturate at lower levels in hotter water so would stay as larger bubbles longer (until the water cooled down in the bulk water and then outgassed).

When such bubbles are larger, as are formed at slower flow rates, they are much more visible. At higher flow rates the bubbles would be much smaller (torn away from the SWG cell plate much more quickly).

This is an interesting effect, but unfortunately other than using the higher flow rate when the SWG is turned on, I don't know a great way to resolve this. Using a longer pipe as I had originally suggested probably won't help that much unless it was quite long (50'?).

I wonder why you see this whereas most SWG installations do not? The short distance probably contributes to the problem, but I wonder how long the pipes have to be to have the hydrogen gas bubbles break up or otherwise become less visible. Has anyone else tried running their pools with low-speed on the pump with the SWG on and seen this effect?

Richard

 

[cobra46]

I run my intelliflow on the lowest speed that I reliably get a green flow light on my SWG which is about 1300RPM. I see small bubbles from my closest return which is about 20 feet from the pump. My bubbles are not as small nor numerous as the OP's

 

[Shieldsfx]

Richard,

After all the tests and the analysis , I agree with you that the milky substance spewing out of the jets is hydorgen bubbles, and these are produced when 1) SWG is on, 2) the pump is set a low flow rate and 3) the heater is on. I also agree that the distance of the pipes could make a difference (as confirmed by Cobra's input), but my situation is not able to confirm this as a key factor, since all my pipes are within 20 feet or less from the SWG; the substance was notes on all jets. What is not understood is why my problem is particularly bad (or the milky substance so obvious).

My theory as to why my problem is particularly bad is "temperature". I have a near 400,000 BTU heater and when the pump is set at the low flow rate, the temp of the water coming from the jets is extremely hot (not scolding) but uncomfortable. I believe the low flow allows the water to become much hotter at the SWG, exacerbating the hydrogen bubble issue. At faster flow rates (or longer pipe distances between SWG and pool/SPA) the water cools sufficiently to minimize the appearance of the bubbles.

I don't think there is much more to do here, except for me to turn up the flow rate. I am curious if anyone else has similar conditions to confirm my theory or duplicate this situation?

I do indeed appreciate your help here and welcome further feedback or questions.
Fran