Free chlorine

[meade]

With my test kit (hth 5-way) I can get a total chlorine level. I have been keeping it around 3.0 to 3.5. My CYA is at 30. I am not understanding the FC and why it is important. Is there a real need to know the FC and can I assume that when I check the chlorine levels that what is left in my pool at the end of the day is FC?

Meade

[littleHeidi]

This is my understanding of it. I still haven't quite gotten the hang of this but I'm sure an expert will post sooner or later and explain in more detailor let me know what I got wrong. Here's a quick formula for the chlorine: TC-FC=CC. FC is the good chlorine that you want to have in the pool. It's what combats all the "gunk" in your pool. CC is "bad" chlorine. If this number is high, it means your chlorine isn't doing you much good. Ideally, you want this number (CC) to be 0 and you want the TC and FC numbers to be the same. You can do a search on this site and read ALL about what these numbers mean in relation to one another and why they're important to know. Again, someone PLEASE let me know if I got any of this incorrect. This is what I've gleamed from reading this site and the sister site. I noticed noone else had posted yet and thought a LITTLE information was better than nothing for ya.

[meade]

Thanks littleHeidi, I appreciate the info. My pool is in sunlight all day and gets alot of use. I am having to bring up my chlorine content every nite which I understand but with my test kit I have no idea in the FC and CC. I just wondered if knowing this is that crucial or not.

Meade

[CarlD]

LH,
You pretty much nailed it.

[jereece]

Maybe just another way of saying it.

Free Chlorine does the job of killing bacteria and oxidizing contaminants. When you add chlorine to the water, you are adding Free Chlorine. When the Free Chlorine reacts with contaminants such as oils, bacteria and organics, it becomes combined chlorine. Combined chlorine has little sanitizing ability, and no oxidizing ability. Therefore, if the total chlorine level is higher than free chlorine, that indicates the presence of combined chlorine. In that case you need to shock or superchlorinate your pool.

Jim

[littleHeidi]

Maybe just another way of saying it.

Free Chlorine does the job of killing bacteria and oxidizing contaminants. When you add chlorine to the water, you are adding Free Chlorine. When the Free Chlorine reacts with contaminants such as oils, bacteria and organics, it becomes combined chlorine. Combined chlorine has little sanitizing ability, and no oxidizing ability. Therefore, if the total chlorine level is higher than free chlorine, that indicates the presence of combined chlorine. In that case you need to shock or superchlorinate your pool.

Jim

Show off!!;)

Seriously, thanks for articulating that for me, Jim.

[meade]

Combined chlorine has little sanitizing ability, and no oxidizing ability. Therefore, if the total chlorine level is higher than free chlorine, that indicates the presence of combined chlorine. In that case you need to shock or superchlorinate your pool.

If my test kit only checks TC, will I see a change in the pool if CC it higher than FC that will trigger me to superchlorinate it?

[Simmons99]

Although a good test kit is the better choice. CC can leave a chlorine odor. If the pool is cloudy that will also let you know to shock the pool.

[Rangeball]

No, your test kit won't.

To specifically test for free chlorine, you need to get a different drop based kit that specifies it specifically tests for FC.