Just being curious...

slepax

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Jan 30, 2014
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Perth, Australia
#1
Hello,

I have no issues with my pool, the TFP way has been working great for more than a year now!!! Just two questions that I am curious about:

- What if in the middle of a SLAM, with say 25ppm FC, I will jump into the pool for a short swim? What would the effect on my skin, eyes, hair?

- Is SLAM levels safe for the pool? Can it damage the surface in any way? And what if it's an old fibreglass or old tiled pool?

Thanks!
 

tim5055

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#2
Both you and the pool are safe up to and even above full SLAM FC levels.

Remember, CYA is the key. In your example 25 FC would be hard on you and your pool/clothes if the CYA was only 20 but fine if your CYA is 200.
 

pwrstrk

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#3
SLAM level won't hurt a thing as long as your at the correct SLAM level for the CYA level. The CYA acts as a buffer taking the harshness out of the chlorine.
You can swim in FC level's up to SLAM level without any problems. Pool surfaces and equipment will also be fine. 😎
 

duraleigh

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#4
The SLAM values that we suggest are not just random, "Let's say this will work" levels. Rather they are levels based on solid science and thousands of pool owners experience.

TFP has no intention of suggesting you do something when we have no idea of the effect. In fact, a principle we teach within TFP is understanding exactly what will take place before you make additions to your pool water.
 

slepax

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Jan 30, 2014
31
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Perth, Australia
#5
Thanks guys for the replies.

Perhaps I missed something regarding CYA. Assuming CYA of 80ppm, the target FC is 6ppm and SLAM FC is 31ppm. This is quite a jump from 6 to 31 using the same CYA levels, wouldn't that make the chlorine far more effective and damaging?
 

pwrstrk

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#6
Chemgeek can give a more detailed explanation, but for a given CYA level the shock FC level is where the chlorine will kill algae. This has been proven scientifically. The target FC level's will prevent algae from developing as long as you don't fall below the min FC level for the CYA level.
Again the CYA is a buffer for the chlorine.
 

duraleigh

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#7
At the risk of being repetitive....
Rather they are levels based on solid science and thousands of pool owners experience. TFP has no intention of suggesting you do something when we have no idea of the effect. In fact, a principle we teach within TFP is understanding exactly what will take place before you make additions to your pool water.
More effective - Yes, that's the idea of a SLAM.
 

slepax

Active member
Jan 30, 2014
31
0
Perth, Australia
#9
Here's an article that somewhat explains the answers to your question further.
Thanks for the link, it definitely helped with my questions.

One more question that I now have from ready the article, it says:

"The levels above assume that you are testing water from a well-circulated pool, with a decent flow distribution. Most home pools with pumps running on high meet this requirement."

My thinking was that running the pump on low for a longer period was more efficient, was I wrong?
 

JasonLion

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#11
If the pump has been running for an hour at whatever speed the water is well mixed. There can be exceptions, especially for complex shapes with few returns, but they are not all that common.
 

chem geek

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Mar 28, 2007
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#12
Perhaps I missed something regarding CYA. Assuming CYA of 80ppm, the target FC is 6ppm and SLAM FC is 31ppm. This is quite a jump from 6 to 31 using the same CYA levels, wouldn't that make the chlorine far more effective and damaging?
It fortunately takes fairly low levels of active chlorine to prevent algae growth. In a saltwater chlorine generator pool, a Free Chlorine (FC) level that is roughly 5% of the Cyanuric Acid (CYA) level is the minimum needed to prevent green and black algae growth. This is roughly equivalent to having only 0.04 ppm FC with no CYA. As you can see, CYA significantly moderates chlorine's strength. The SLAM level is roughly an FC/CYA ratio of 40% and is equivalent to having 0.6 ppm FC with no CYA. So yes, the active chlorine level is roughly 15 times higher and would oxidize swimsuits, skin, and hair roughly that much faster, but it is not at a level as high as most commercial/public indoor (and some outdoor) pools where CYA is typically not used. So consider that your day of swimming at this level would be equivalent to swimming for 15 days at normal TFP pool levels, but not even as much as one swim in a commercial/public pool with no CYA.

As noted in this paper, eye irritation was strongly associated with chloramines, but not with chlorine levels at 1 ppm FC with no CYA unless there was little salt in the water. At 7000 ppm salt, the eye irritation went away (unless chloramines were present) indicating that the salt level is the more relevant factor and is why SWG pools at 3000 ppm are less irritating to the eyes. It's likely the increased osmotic pressure of water entering into the eye in non-salt pools that is the cause of most eye irritation, though in commercial/public pools where chloramines are present then those are most irritating.

Nevertheless, we do not recommend swimming at SLAM levels on a regular basis. People ask if they can swim and the answer is yes. It won't be dangerous, but it's not what you would normally do, not so much because of the high chlorine levels but usually one SLAMs when there is algae and often the water is cloudy and pool surfaces might be slippery. If the water is so cloudy that one cannot clearly see the bottom of the pool, then it would be dangerous to swim in that situation as one could not see a drowned person at the bottom of the pool.
 

duraleigh

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#13
Nevertheless, we do not recommend swimming at SLAM levels on a regular basis. People ask if they can swim and the answer is yes. It won't be dangerous, but it's not what you would normally do, not so much because of the high chlorine levels but usually one SLAMs when there is algae and often the water is cloudy and pool surfaces might be slippery. If the water is so cloudy that one cannot clearly see the bottom of the pool, then it would be dangerous to swim in that situation as one could not see a drowned person at the bottom of the pool.
Well said! :D That response is so clear it requires repetition so lots of people see it.