Combined Chlorine

[Socal76]

I have a question regarding combined chlorine.

My understanding is that Combined Chlorine is bad because it's chlorine that has been used up sanitizing the water. Wouldn't the sun eventually remove the CC just like it would remove FC. I've seen alot of guidance to shock the pool to remove the CC? Wouldn't this shock just turn into more CC?

Also, if it's healthy to check and dose your pool daily with bleach if necessary, what about hired pool cleaners that come once a week. Wouldn't that leave the pool neglected for an entire week?

Thanks in advance. I'm learning so much everyday.

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If i left CC in the pool, would the sun eventually remove it?

 

[ewkearns]

I have a question regarding combined chlorine.

My understanding is that Combined Chlorine is bad because it's chlorine that has been used up sanitizing the water. Wouldn't the sun eventually remove the CC just like it would remove FC. I've seen alot of guidance to shock the pool to remove the CC? Wouldn't this shock just turn into more CC?

The accumulation of CC is bad.... because (as you suspect) the sun should remove it (as well as FC). The shock *could* turn into more CC if there was anything to burn off, but in a properly maintained pool all it does is blindly increase the FC. The assumption is that "shocking" the pool gets rid of everything bad that we don't know or understand. As clever pool managers, we don't ever have that condition.

Also, if it's healthy to check and dose your pool daily with bleach if necessary, what about hired pool cleaners that come once a week. Wouldn't that leave the pool neglected for an entire week?

Absolutely! That is why they live and die by the use of solid chlorine and "shocking" and "chlorine lock" and ever increasing CYA and suggesting that you drain your pool because the TDSs have caused an imbalance in the force..... OK, I'm goofing around, but turning your back on a pool for a week is just begging for things to get out of hand. Paying somebody to do this for you is just nuts.

If i left CC in the pool, would the sun eventually remove it?

I'm going to say, "yes," but that assumes you continuously have enough FC to prevent growth of nasties that would continuously add (possibly without bounds) to the original CC.....

 

[Socal76]

So if a pool has a high CC, the correct step is to wait for the sun to remove it? I guess that depends how bad the CC level is.

 

[Sub-trop-tech]

Combined chlorine or chloramines is usually the cause of "Chlorine smell", if any, in pools. It is used up chlorine and will dissipate on its own. What area is your pool located in?

Sent from my QMV7B using Tapatalk

 

[Richard320]

So if a pool has a high CC, the correct step is to wait for the sun to remove it? I guess that depends how bad the CC level is.

No.

Consider CC to be halfway used chlorine.

Bleach is an oxidizer. So is fire. Think of it as flameless combustion. Sodium Hypochlorite NaOCl breaks down in water to NaCl (salt) and O^- oxygen ions that react with other compounds.

Something organic - leaves, grass, algae, dead skin, snot, pee, anything - reacts with the bleach and hopefully disappears. Just like when you burn something - you hope you get nice hot flames and no smoke and no soot. What happens if the fire doesn't get enough oxygen? Smoke, soot, ash, and smell. That's pretty much what CC is. Incomplete combustion.

How do you get the fire going better to eliminate the smoke? Add more oxygen by fanning or blowing or using a bellows. How do you get the pool reaction going better - add more oxygen by adding more bleach.

 

[Mike1162]

So if a pool has a high CC, the correct step is to wait for the sun to remove it? I guess that depends how bad the CC level is.

No. You want to increase the chlorine level to completely break down whatever is causing the problem.

Try reading the following Pool School link until someone with more experience can give you a better explanation.
http://www.troublefreepool.com/content/123-abc-of-pool-water-chemistry

Edit - Rich already posted the better explanation.

 

[ewkearns]

Maybe more than you wanted, but here is the full explanation:

http://www.troublefreepool.com/threads/17328-Is-the-formula-for-quot-Superchlorination-quot-or-quot-Shock-quot-too-high

 

[chem geek]

There are different types of CC. As Richard pointed out, it's sort of halfway on its way to getting oxidized by chlorine. It's chlorine combined with ammonia or an organic, but chlorine hasn't actually oxidized it yet.

Some CC breaks down in sunlight (such as dichloramine) while other CC does not. Some gets further oxidized by chlorine relatively quickly (ammonia), some slowly (urea), and some is persistent.

Generally speaking, in an residential pool that is typically low bather-load and exposed to sunlight, CC levels will be low and we don't care about it unless it gets higher than 0.5 ppm (i.e. <= 0.5 ppm is OK).

 

[Socal76]

Thanks everyone for being so helpful!