Safe Cl levels for swimsuits when using CYA/Cl chart.

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lalittle

Well-known member
Apr 4, 2011
184
Los Angeles, CA
I'm curious what levels of Cl are still safe for both swimming and for swimsuits when using the recommended Cl levels given on the TFP CYA/Chlorine charts. In order to make things a bit easier and not have to add Cl nearly every day, I'd like to raise the FC levels above the "target" levels, and perhaps even above the "Yel/Mstrd Min" listed in the chart that has this column, but I'm a bit unclear at what point the Cl level starts to cause problems for the fabric in swimsuits.

For example, for a CYA of 60, the chart lists a "minimum" C level of 4.4, a "target" of 6.8, and a "Yel/Mstrd Min" of 9.0. I find that my pool can start to get a bit of algae in the shady areas if I let it go all the way down to the "min" level, so in this situation I'd like to use a minimum of about 6. When I add Cl at this point, how high can I put it before it starts becoming a problem? In my 22K gallon pool, a gallon of 12.5% liquid Chlorine gives me about a 6.5ppm rise in Cl. This, however, would put me to 12.5ppm. This is still well below the shock level of 23.7, and I'd think it would still be fine on skin, but would it still be okay for swimsuits, including elastic and more delicate materials? If I instead add a half gallon of 12.5% liquid Cl, that would put me a bit above 9, which is essentially at the ""Yel/Mstrd Min," but if I added it a day early, that might give me closer to 10 or 11. Would this still be safe on swimsuits?

Thanks for feedback on this,

Larry
 
Hi Larry,
Its safe for both swimmers and suits all the way up to SLAM level.

There is a search box just under the pool school button. THere are lots of the same answer if you google safe FC or something of the sort.

Hope this helps,
 
Smykowski said:
Anything below shock level is fine. I'm on the same swimsuit for the last 3 years, and I tend to run my FC at or slightly above the top of the recommended range.

Just be aware that keeping FC near shock level as a maintenance target is really inefficient due to burnoff from sunlight.
Click to expand...

I'm not entirely sure what "slightly above the recommended range" would mean. Are you referring to the "target" or the "Yel/Mstrd Min"? Could you give me an example of your CYA and Cl numbers -- i.e. what's your CYA, how high do you boost your FC level when you add Cl, and how far do you let the FC drop before adding again?

Thanks.
 
Sure....my CYA is at 50. According to poolmath, my recommended FC range is 4-8. I usually add bleach when it gets down to 7 and I target 10-11. I know that this is slightly inefficient and that I'm losing a little more to sunlight, but I'd rather run a larger buffer above the min so that if I get lazy/miss a day, I have a cushion to work with.
 
To put things into some perspective, the following gives the FC equivalent with no CYA at the various FC/CYA levels in the chart.

FC/CYA Level . FC with no CYA @ 77ºF . FC with no CYA @ 90ºF
SWG 4.5% ............... 0.036 ............................ 0.09
non-SWG 7.5% ......... 0.06 ............................. 0.16
Target 11.5% ........... 0.10 .............................. 0.26
Yel/Mstrd 15% .......... 0.14 .............................. 0.35
Shock 40% .............. 0.61 .............................. 1.17
Y/M Shock 60% ........ 1.42 .............................. 2.18

So you can see that swimming up to normal shock level has the chlorine not even be as strong as commercial/public pools that have no CYA since they are required (in the U.S.) to have at least 1 ppm FC. The main issue with a high FC level is if you were to ingest the water though even then you'd have to drink a lot of water every day since the EPA limit is 4 ppm for 2 liters per day for a lifetime.

You will likely notice a difference at the higher chlorine level, but not so much in terms of swimsuits but in terms of smelling the faint clean chlorine bleach-like smell especially if you churn the water. You are only talking about yellow/mustard target level (not shock level) so it's not that high. Nevertheless, it's still subtle to many people, though some people have a very sensitive sense of smell.

The main difference you will notice will be the higher chlorine loss, but that's the trade-off for not having to add chlorine as frequently.
 
Hi Larry,
here is a link to recommended levels. There is also a link within that will provide even more detailed levels.
http://www.troublefreepool.com/content/134-recommended-levels


lalittle said:
I'm not entirely sure what "slightly above the recommended range" would mean. Are you referring to the "target" or the "Yel/Mstrd Min"? Could you give me an example of your CYA and Cl numbers -- i.e. what's your CYA, how high do you boost your FC level when you add Cl, and how far do you let the FC drop before adding again?

Thanks.
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