Cloudy water from pool return when SWG running

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flex727

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Apr 2, 2010
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I have an IntelliChlor SWG and over the last couple of years I've begun to see cloudy water coming from the pool returns while the SWG is operating. It was not noticeable 3 years ago, last year I started noticing it and became concerned, and this year it is unmistakable - very white cloudy water exiting from the returns that clears up quickly when the SWG cycles off. The pool water is crystal clear away from the returns and the cloudiness fully dissipates when the SWG is turned off. I follow the BBB method and the water chemistry is very well balanced. Latest test:

FC - 3
pH - 7.6
Borates - 45
TA - 90
CYA - 50
Salt - 3200
Temp - 69F
CH - 430

I use cartridge filtration and the filters were recently cleaned.

Any thoughts?
 
It may be just tiny bubbles of hydrogen gas that are released from the water during the electrolysis that produces the chlorine.
 
It could also be calcium flaking off the cell although that usually looks small flakes rather than a cloud. Have you cleaned or inspected the cell lately?
 
This usually happens when you are using a SWG with a pump on low speed. The slow water movement tends to concentrate the small hydrogen bubbles that the SWG always makes and causes them look like a cloud. The cloudiness dissipates fairly rapidly, as the hydrogen either dissolves into the water or the bubbles make their way to the surface and pop. If this is the cause, it doesn't do any harm. Speeding up the pump can make the cloudiness go away because then the bubbles will be much more spread out and won't look like much unless you look very closely.
 
Immediately following cartridge filter cleaning and for the next few days, the water may become noticeably cloudy as the filter runs. This is a normal effect of the cleaning process, but may not occur every time you clean your cartridge. This may be one additional factor affecting the sudden loss in clarity of your water.
 
I think JasonLion may have nailed it. The cell is clean and there are no precipitates, however, I did just reduce the pump speed for the filtration process. While I recognize that this isn't harmful, it IS unsightly. Is there anything I can do to reduce the cloudiness other than to increase the pump speed?
 
Oh, and thanks to JohnT also.

I've looked more closely at the cloudy water and it does indeed appear to be millions of tiny bubbles, but it sure does seem excessive. I have the valving set to allow some return water to enter the hot tub (from the center bottom, not the bubbler jets) and when the SWG cycles on it looks like I've poured 10 gallons of milk in there. This can't be right. What could cause excessive Hydrogen production from the cell?
 
flex727 said:
What could cause excessive Hydrogen production from the cell?
Click to expand...

Hydrogen production is an unavoidable part of the chlorine production process. If you aren't producing hydrogen, you aren't producing chlorine.
 
The hydrogen production of the cell is essentially constant. But the number of bubbles coming out of the return varies somewhat depending on your other chemistry numbers. Hydrogen dissolves into the water and/or bubbles up to the surface at different rates, depending on various other levels. The only one we are sure of is pump speed. Higher pump speeds make the bubbles less visible. I also believe, but haven't confirmed, that higher temperatures will mean more of the hydrogen will dissolve into the water, making the cloud less visible. I know that several other things affect it as well, but I am not sure exactly what they are.
 

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Thanks again, JohnT & JasonLion. Maybe this will clear up somewhat as the pool warms, and I can certainly return the pump to a higher speed (I've got it set to turn the pool over in 12 hours - 25 GPM), but it sure seems like something is amiss here. I have read everything I could find and talked a lot of different people, and while everyone agrees that bubbles are normal and unavoidable, no one has seen a situation where the pool looks like slightly diluted milk.
 
I have heard of it before a couple of times. It always happens with low speed pumps, usually in the spring. SWGs are normally optimized for high speed, and they don't put as much thought into how they work at low speed. Also, there are various chemical levels that affect how the cloud looks. I don't know what the specific things are that affect it, but I do know that your clouds won't always be as obvious as they are now. I suggest balancing your levels and seeing if the appearance changes.
 
One thing that I wonder about from your numbers: Your CH at 430ppm. Calcium can make water behave a little differently with regard to foaming and bubbles. Anybody have any thoughts about the idea that the slightly high calcium level could make the hydrogen more prone to remain as bubbles in this situation?
 
Poolsean said:
Flex, do you have a heater, and is it running right now?
Are the bubbles coming out of all your return jets or one or two in particular?
Click to expand...
Yes, I have a heater (Pentair 400K BTU gas), but I'm not running it right now. The bubbles are uniformly coming out all 5 pool returns and the "feature" return in the spa.
 
Well, I think I may have found the problem. The cell looked pretty clean, but I thought I might as well run some MA through it anyway. I poured about a half gallon of 50/50 mix through it, rinsed it off and put it back in line. The cloudiness seems to have been reduced by at least 90%. I can still see it, but it's now not nearly as unsightly. Not sure what the mechanism was for the bubble generation but it seems to be alleviated for now.

File this away for future reference.
 
this can also happen when a chemical is added to the water which contains Benzyl ammonium chloride, normally found in algaecides and you have cloudy water returning back to your pool. switch the swc off and the cloud stops. switch the filtration off and after a short period the cloudiness in the pool disappears. This is also known as quaternary compond or quats.
 
A little followup:

A few days after my initial cleaning of the SWG cell, I started getting cloudy water from the returns again. Not as bad as before, but definitely the same thing. I thought perhaps I did a poor job of cleaning the cell, so I borrowed a Pentair cleaning kit (it's just a screw on cap with an o-ring) from a pool tech and cleaned it properly with an acid solution and letting it soak for about 10-15 minutes. There wasn't much bubbling during the cleaning process like you would expect, but after putting it all back together, the cloudy water issue is completely gone. I'm hoping it stays gone for awhile this time. I probably need to work my CH down a bit to make this a more lasting clean.

Thanks to all who jumped in to help.
 
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