I know I read it somewhere on here. I am a new hot tub owner, and I'm looking for info on chlorine. TC should be zero? How do they all relate? CC is really used up chlorine? Thanks in advance.
Mike
Mike
Point me in the right direction: FC, CC, TC.
- Thread starter Madison Mike
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TC is total chlorine, and is the sum of FC (free chlorine) and CC (combined chlorine). Combined chlorine is chlorine that is combined with something, like ammonia, that reduces chlorine's ability to oxidize effectively.
CC should be zero, or near zero. TC should equal FC.
CC should be zero, or near zero. TC should equal FC.
Thanks guys. I'm still unsure about how this works.
In the ABC's of Water Chemistry, the first sentence in the FC definition is: "Maintaining an appropriate FC level is the most important part of keeping your water in balance." Is "in balance" the correct wording for this, or would "keeping your water sanitized" be better. When I think of balanced water, I think of pH, TA, CH, and water temp.
Under the CC definition, the term SLAM is mentioned. As a newby, it took me a while to find the link to slamming your pool. A hot link on SLAM here would be very helpful.
So, here's an example situation. I have a pool that is correctly balanced, and an FC level of 4. I add an ounce of bather waste. The chlorine goes to work and oxidizes this waste and kills bacteria. Would there ever be any CC in this process, because there was enough FC to do the job? Would it be correct to say that if my CC is above 0.5, then my FC is used up? If this happens, I slam the pool, or shock it, to stay on top of the waste..
I'm close, but I'm still not completely understanding the chemistry here.
In the ABC's of Water Chemistry, the first sentence in the FC definition is: "Maintaining an appropriate FC level is the most important part of keeping your water in balance." Is "in balance" the correct wording for this, or would "keeping your water sanitized" be better. When I think of balanced water, I think of pH, TA, CH, and water temp.
Under the CC definition, the term SLAM is mentioned. As a newby, it took me a while to find the link to slamming your pool. A hot link on SLAM here would be very helpful.
So, here's an example situation. I have a pool that is correctly balanced, and an FC level of 4. I add an ounce of bather waste. The chlorine goes to work and oxidizes this waste and kills bacteria. Would there ever be any CC in this process, because there was enough FC to do the job? Would it be correct to say that if my CC is above 0.5, then my FC is used up? If this happens, I slam the pool, or shock it, to stay on top of the waste..
I'm close, but I'm still not completely understanding the chemistry here.
See if the following helps. It's in the deep end, so swim carefully....
http://www.troublefreepool.com/showthread.php?p=619895
What is TDS?
http://www.troublefreepool.com/showthread.php?p=619895
What is TDS?
Bottom line is, no, you shouldn't see CCs. (Nearly) as fast as they are formed, sunlight will break them up.
Your FC must be continually replenished because it will be lost to sunlight and it will be consumed in the sanitation and oxidation process. As long as you keep your FC in range for your CYA level, there will always be enough FC to keep the pool clean.
Your FC must be continually replenished because it will be lost to sunlight and it will be consumed in the sanitation and oxidation process. As long as you keep your FC in range for your CYA level, there will always be enough FC to keep the pool clean.
Sorry, just realized that we're in the hot tub sub forum (tricked by tapatalk!).
My understanding is that because there's much less sunlight, CCs will go through all the iterations before being completely oxidized. Either way, if you follow our FC/CYA relationship recommendations, you won't have a problem.
My understanding is that because there's much less sunlight, CCs will go through all the iterations before being completely oxidized. Either way, if you follow our FC/CYA relationship recommendations, you won't have a problem.
First, there are others that can explain this better but I'll try. You could (for example) start with an FC of 4, add bather waste, then measure FC of 2.5, CC of 1 (TC was 4=4+0 but now TC is 3.5=2.5+1.0 and some chlorine is simply gone away). The CC is an intermediate step, chlorine in the process of being used up. Not useful in this form, actually a sort of waste product, gives the pool that "chlorine smell".
That CC will go away eventually, probably using up some of that remaining FC as it does and depending on things like sunlight and wind, for example.
In this example, if you tested and measured FC down to 2.5 and CC of 1.0 you would certainly increase FC back to 4 or to the top of the recommended range for your CYA level, maybe a touch more, and you'd probably be sure to not cover the spa so that CC's might benefit from air circulation to help them disperse. If, say tomorrow, you still saw CC's high, you might slam the spa but really, it's probably get back to a normal 0 to 0.5 ppm CC pretty fast as long as you were keeping the FC up. If you let the FC go to zero, then that is a different issue for the CC's will have a harder time going away and FC of zero is never good for keeping things sanitary.
Now, if the spa got nasty for some reason. Say you found a dead critter in the water, really ugly. Probably you'd dump water and start over but if you chose to not do that you'd shock or slam the spa. You'd find FC low or at zero, raise it up to shock/SLAM level, and the CCs would get raised or even really high as the crud was being burned up by the chlorine. CCs drift lower as all the crud is sanitized.
- - - Updated - - -
First, there are others that can explain this better but I'll try. You could (for example) start with an FC of 4, add bather waste, then measure FC of 2.5, CC of 1 (and some chlorine is simply gone away). The CC is an intermediate step, chlorine in the process of being used up. Not useful in this form, actually a sort of waste product.
That CC will go away eventually, probably using up some of that remaining FC as it does and depending on things like sunlight and wind, for example.
In this example, if you tested and measured FC down to 2.5 and CC of 1.0 you would certainly increase FC back to 4 or to the top of the recommended range for your CYA level, maybe a touch more, and you'd probably be sure to not cover the spa so that CC's might benefit from air circulation to help them disperse. If, say tomorrow, you still saw CC's high, you might slam the spa but really, it's probably get back to a normal 0 to 0.5 ppm CC pretty fast as long as you were keeping the FC up. If you let the FC go to zero, then that is a different issue for the CC's will have a harder time going away and FC of zero is never good for keeping things sanitary.
Now, if the spa got nasty for some reason. Say you found a dead critter in the water, really ugly. Probably you'd dump water and start over but if you chose to not do that you'd shock or slam the spa. You'd find FC low or at zero, raise it up to shock/SLAM level, and the CCs would get raised or even really high as the crud was being burned up by the chlorine. CCs drift lower as all the crud is sanitized.
The bather load in a spa is much, much larger than in a residential pool because the volume of water is so much smaller. In a residential pool, most chlorine is lost due to sunlight, not to bather load, and you don't notice chlorine demand from bather load in a pool unless you have a lot of people in it as with a swim party. In a hot tub, just one person is noticeable.
So with the bather load there is bather waste and it needs to get oxidized by chlorine. During this process, it forms CC. There are many different chemicals and they get oxidized at different rates, but in a hot spa it's usually mostly oxidized within 8-12 hours so is ready for your next soak usually the next day (some people soak twice a day, but most are once a day or less) when the CC will be close to zero (just make sure you are adding enough chlorine so that the FC doesn't get to zero). If you can keep your cover off for a half-hour or an hour after you add chlorine right after your soak, then a good deal of the by-products will outgas (most is nitrogen gas and carbon dioxide, but some are smelly volatile chlorinated disinfection by-products). Also, if you take off the cover for 10 minutes or more before getting into the spa, then that also helps remove what has outgassed over the subsequent hours after spa use.
So with the bather load there is bather waste and it needs to get oxidized by chlorine. During this process, it forms CC. There are many different chemicals and they get oxidized at different rates, but in a hot spa it's usually mostly oxidized within 8-12 hours so is ready for your next soak usually the next day (some people soak twice a day, but most are once a day or less) when the CC will be close to zero (just make sure you are adding enough chlorine so that the FC doesn't get to zero). If you can keep your cover off for a half-hour or an hour after you add chlorine right after your soak, then a good deal of the by-products will outgas (most is nitrogen gas and carbon dioxide, but some are smelly volatile chlorinated disinfection by-products). Also, if you take off the cover for 10 minutes or more before getting into the spa, then that also helps remove what has outgassed over the subsequent hours after spa use.
Thanks, folks. I decided I'd not go to the deep end, and just take your word for it.
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