Bacteria in water?

[jay9suited]

We installed a pool last year so I am newer pool owner. So far this year I have been on top of balancing the water and things have been within range all year with crystal clear water. I have a 1 year old and 3 year old and over the last 2 weeks we've been swimming a lot more with the warmer weather but whenever they swim in the pool they have diarrhea shortly after. We are pretty sure that it must be something in the water because it only happens during/shortly after swimming. Any thoughts? I have never shocked the pool just because everything has been in range. Here is a current reading which isn't far off from how things have looked all year:

PH 7.4
FC 2.5
TA 100
CH 200
Salt 4200
CYA 50

 

[JoyfulNoise]

Possible. You can’t really know unless you do an overnight chlorine loss test. That will tell you if you have anything biological growing in the water.

Also, since these are young children, are they gulping up and swallowing a lot of pool water? Kids are known to do that. Your water has very high TDS from the salt and that kind of water can easily cause a nutrient imbalance (from too much sodium) in their gut. That imbalance can lead to diarrhea because their bodies are trying to flush out all the excess sodium.

If they are gulping water, you need to instruct them to not do that.

 

[dfwnoob]

I'd put money on it being caused by drinking the salty water, especially at that level. The same things happen to my two dogs if we don't get on them immediately about drinking the water.

 

[jay9suited]

Possible. You can’t really know unless you do an overnight chlorine loss test. That will tell you if you have anything biological growing in the water.

Also, since these are young children, are they gulping up and swallowing a lot of pool water? Kids are known to do that. Your water has very high TDS from the salt and that kind of water can easily cause a nutrient imbalance (from too much sodium) in their gut. That imbalance can lead to diarrhea because their bodies are trying to flush out all the excess sodium.

If they are gulping water, you need to instruct them to not do that.

They definitely drink more pool water then we'd like.. we've been swimming all summer but this issue has just come up over the last week or two. TDS hasn't increased as of late.

 

[JamesW]

FC/CYA Levels

 

[jay9suited]

If high salt is the issue, would lowering to 3600 make a difference? Kids are going to drink the water.. I don't want to partially drain if this would still be an issue at a slightly lower TDS.

 

[Flying Tivo]

If its a pentair SWG, it can run as low as 2800ppm. That is what i run my IC-40.

 

[PoolStored]

It is possible that you are also flirting with the low end of enough HOCl to kill bacteria in the pool. See dotted lines for your FC and CYA. With a high bather load, it is possible your FC was below 2.5 and there was some active bacteria. Also, CYA measurement is not that accurate.

I would recommend that you follow the FC/CYA recommendations on the link at the end of this sentence, and maintain your FC higher and in range...Link-->FC/CYA Levels

 

[JoyfulNoise]

If high salt is the issue, would lowering to 3600 make a difference? Kids are going to drink the water.. I don't want to partially drain if this would still be an issue at a slightly lower TDS.

That’s not going to help. The water is too high in sodium as all pool water would be. It’s also pool water which is … gross. You simply have to teach them not to drink pool water and deal with the diarrhea if they do. Sometimes if you make a fuss about it, they’ll not want to do it. When all my kids were little I taught them to put their faces in the water and blow bubble. When they could understand I made sure they knew that pool water is yucky and not to drink it.

 

[jay9suited]

It is possible that you are also flirting with the low end of enough HOCl to kill bacteria in the pool. See dotted lines for your FC and CYA. With a high bather load, it is possible your FC was below 2.5 and there was some active bacteria.

I would recommend that you follow the FC/CYA recommendations on the link at the end of this sentence, and maintain your FC in range...Link-->FC/CYA Levels

View attachment 587969

Interesting. I wonder if this is the issue.. I had thought 1-3 was target FC. So 60-90 CYA is ideal and at current 50CYA level I should target 3-8 FC? We had high FC last fall that bothered our kids eyes so I have been working hard to keep it around 2 this year.

 

[PoolStored]

Interesting. I wonder if this is the issue.. I had thought 1-3 was target FC. So 60-90 CYA is ideal and at current 50CYA level I should target 3-8 FC?

ABSOLUTELY! Keep it in range when you test. If you have to dose higher, so you are always in range when you test, you are golden at killing bacteria.

We had high FC last fall that bothered our kids eyes so I have been working hard to keep it around 2 this year.

It is not FC (high anyway) that causes irritation, it is pH, or swimmer behavior. pH at or above 7.6 and eye irritation is exceeding rare. Keep your pH 7.6 and above. Low FC levels encourage the formation of CC, which is one of the leading causes of eye irritation. You are *maybe* seeing that with the low FC relative to the CYA is causing irritation.

Wear goggles or try to teach your child to NOT rub their eyes. Most pool water irritation in balanced pools is due to people rubbing their eyes when they come up out of the water. It forces the pool water into the conjunctiva where the chlorine will slowly irritate the delicate tissue. When you come up out of the water, you need to teach them to blink their eyes. That will clear the water.

I keep pH 7.6 or above, 80 CYA and 8-10 FC, with 4 grandkids, with an without goggles, or have taught them to not rub. ZERO issues.

 

[jay9suited]

ABSOLUTELY! Keep it in range when you test. If you have to dose higher, so you are always in range when you test, you are golden at killing bacteria.


It is not FC (high anyway) that causes irritation, it is pH, or swimmer behavior. pH at or above 7.6 and eye irritation is exceeding rare. Keep your pH 7.6 and above. Low FC levels encourage the formation of CC, which is one of the leading causes of eye irritation. You are *maybe* seeing that with the low FC relative to the CYA is causing irritation.

Wear goggles or try to teach your child to NOT rub their eyes. Most pool water irritation in balanced pools is due to people rubbing their eyes when they come up out of the water. It forces the pool water into the conjunctiva where the chlorine will slowly irritate the delicate tissue. When you come up out of the water, you need to teach them to blink their eyes. That will clear the water.

I keep pH 7.6 or above, 80 CYA and 8-10 FC, with 4 grandkids, with an without goggles, or have taught them to not rub. ZERO issues.

Thanks for the info! If we did manage to get a bacterial will the chlorine rid the pool of it or would I have to do something more than raise the FC?

 

[PoolStored]

FC will kill it. Keep it in range for your CYA. Link-->FC/CYA Levels

 

[JoyfulNoise]

The FC/CYA ratio and recommended levels were designed around the idea of killing and limiting ALGAE growth. While algae grows slower than bacteria, it is far harder to kill algae than most pathogenic bacteria. Bacteria can reproduce faster but they are fragile organisms for the most part and so even with sub-optimal FC/CYA, pretty much any measurable FC level in the water will kill bacteria. So I sincerely doubt the issues your young swimmers are facing are bacterial in any way.

Also, if this is simply diarrhea with no other symptoms like fever, aches & pains, or lethargy, then it’s also unlikely to be a bacterial issue. Most bacteria that cause GI issues will also cause those other symptoms including nausea and vomiting.

 

[jay9suited]

Just an update for anyone interested. We got the FC up to 5.0 and swam yesterday which was the first day in roughly a week that neither child had diarrhea. Hoping that was the issue! I appreciate all the responses!