High Combined Chorine

Recently I have:
- Opened pool for the first time as it was built new in the fall, and the balanced chemicals
- Lowered PH, used stain removal product, raised PH with Borax after stains removed.
- Chlorine was low after stain removal process because SWG was turned off. Then added fresh water to raise the water level, which lowered chlorine to nearly 0.
- After about two hours of kids swimming the water was green and my CC was 2.
- I tried to shock it by bringing the FC up to 15. It wouldn’t go above about 8ppm for the longest time. It took 31 gallons of bleach to get it up there. The next day the pool was clear and the kids swam in the evening.
- Now the FC is back down to 2, but the CC is about 15. So it seems to have made it worse.

Why didn’t that work? What can I do to burn off that amount of CC? Is there another option to buying 30 more gallons of bleach? The water looks clean and doesn’t have much of a chlorine smell, but it doesn’t have that crystal clear sparkle that it had when it was properly balanced.

Thanks.

What kind of test kit are you using? I would think that a CC of 15ppm is unlikely. Did you fill from a well?

I got the Taylor 2005 when the pool was built. I did the dilution method (1.8mL) and it was darker than 5 when I added the thrid drops - about 1 after the second drops. I am on a well, but added softened water from inside the house.

If you buy the Taylor K-1515 which is a stand alone FAS-DPD tester, you'll basically have the K-2006 that we recommend. You can get it through the test kit page in my signature below. It would be a good decision to get it.

OK. I bought the supplemental kit via your link, but regardless I am fairly certain that I have high CC. I like to get this taken care of ASAP as the weather is supposed to be cool this week. What is the best process for eliminating high CC?

The way to get rid of CC is to maintain your chlorine at shock level as consistently as you can. But, in the case of a pool with a metals issue like you have, shocking can cause metals to fall out of suspension and stain. I am going to ask Ben to pop in here on your thread and advise you so, sit tight for now.

Watermom,
I received the K-1515 test kit yesterday and checked the chlorine levels. Here it is:
FC- 2.0, CC – 22 (44 drops of the 10mL test), CYA ~ 30, PH – 7.6 (goes up about .05 per day)
Will some of the CC burn down on its own? It has been 8 days since I added 31 gallons of bleach due to the green color and have been running the SWG since the FC got back down to 2.0-4.0. I am inclined to wait a while because my water looks good and doesn’t have much of a smell, if any. I have been reading about people adding 100+ gallons of chlorine to get their CC down. I am afraid to start the process! Isn’t there a bucket test to estimate how much chlorine it will take? Thanks.

Wow! That's the highest CC I've seen. I'm going email Chem_Geek, and see if he has any ideas.

Meanwhile, please re-read the instructions on the K-1515, and make sure you don't have a testing error.

The 1515 results are consistant with the dilution method, which showed a bright 15+. Unfortunately, I am confident the results are accurate.

It sounds like the pool was opened with ammonia and that you haven't gone through all of it yet. The FC is probably bleed-through from the high CC and not really FC. Keep adding chlorine until the CC starts to decline and you start holding an FC reading. If you want, you can do a bucket test with pool water to estimate how much more chlorine it will take.

Is there a link somewhere for the bucket List procedure? Should I wait to let it come down on its own or start immediately?

The only reason for the bucket test is to see how much chlorine it will take -- but it won't change what it takes at all, or make it easier.

But, if you want to do the bucket test, do this:

1. Add 4 boxes of borax (20 Mule Team brand, added slowly to your skimmer, pump running) to your pool. The conversion process goes more nicely at a higher pH.

2. Get a CLEAN 5 gallon bucket and a bathroom scale. Put the bucket on the scale, and weigh it. Add enough water to the bucket to increase the weight by 33 lbs (4 gallons) - PF:3640

3. Half fill a measuring cup with plain 6% chlorine bleach. Add 1 oz to the bucket (about 14 ppm). Mix, wait 15 minutes, remix, wait 5 minutes. Test the chlorine levels.

4. If the CC level is higher than the FC level, repeat the dose and process.

5. Continue until the CC level begins to be LOWER than the FC level.

6. Add one more dose, then mix and wait 1 hour. Retest. If the CC level is less than 1/4 of the FC level, this is your approximate finishing point.

7. Multiply the number of doses by 14 to determine the total approximate dose required to clean up your pool. Divide this number by 2.7 to determine the number of gallons of bleach required, or by 3.7 to determine the pounds of 68% calcium hypochlorite required.

8. With a gunite pool, you can tolerate VERY high chlorine without a problem. Add 3/4 of the bleach (if you are using bleach) at one time. Do NOT cover the pool; do NOT let the heater or SWCG operate.

9. If you use cal hypo, you must add it slowly via the skimmer, but you must make SURE that there are no tabs, trichlor, ionizers or other chemicals or devices between the skimmer and the filter. Make SURE the heater & SWCG are off. You may need to backwash several times, as the lime dust accumulates on your filter.

10. Again, during this process you MUST leave the pool uncovered, the heater off, the SWCG off, and the pump ON.

Ben,
I am confused where you are getting the 14 and 2.7 numbers. My pool is 22,000 gallons or 2,816,000 oz. Four gallons in the bucket is 512 oz. By ratio, if I add one oz bleach to the bucket that would be equivalent to 5500 oz to the pool, or 43 gallons of bleach. Your numbers say a 1 oz dose is equivalent to 5 gallons of bleach, which is much better, but I am not following the math.
Additionally, according to the pool calculator, adding one oz bleach to 4 gallons will raise the FC by 121. I am not trying to question your theory I am just trying to get the numbers to make sense in my head, as I am a dorky engineer! Thanks.

So I have attempted the bucket test. I calculated that 5mL (0.16 oz) chlorine in 5 gallons of water (15ppm) is equivalent to 5.5 gallons of chlorine in my 22,000 gallons. So my dose in my bucket is 5mL. Here are the results of my bucket:
Before any chlorine: PH – 8.0, FC – 1.0, CC - 18.5
After first dose: FC – 17, CC – 21
Second dose: FC – 32, CC – 33
Third dose: FC – 46, CC – 36

I figured the FC was high enough even though the CC wasn’t 1/4FC. So three doses at 5.5 gallons per dose is 16.5 gallons, but I added 14 gallons to the pool (a little more than 75%). Unfortunately, I used the entire 871 reagent durin the bucket test and before I could test the pool because the chlorine is so high. I’ll have to get some more tomorrow before I can test again. Hopefully Leslies has some.
These seem like some high chlorine levels! Does this seem like I am on the right track?

I doubt Leslie's has any R0871, though you could certainly check. If it's much of a drive, I'd call first though.

But, you are right about the R0871 -- I had overlooked the fact that we need to warn people that the high chlorine & cc levels experienced during ammonia clean burn through the R0871 in a hurry. It's a bit of a problem, since there's no real fast way to get more. I just looked on Amazon, and this is probably your best bet:

Taylor FAS-DPD Titrating (Chlorine) 16 oz R-0871-E

You can refill your R0871 bottle, by popping the tip out (press your thumb on the side of the tip, while holding the bottle, and press), and then refilling. You might want to try doing so BEFORE you order the big refill, since if you happen to ruin the bottle, you won't be able to use the refill. Use CLEAN hands -- you don't want to contaminate the tip or the solution.

Also, if you'll store the pint bottle in the back of your fridge, where it's dark and cool, it should last several season.

Regarding your pool, I'd recommend going ahead and adding a 25 gallon dose of chlorine, at about 7 or 8 PM, so it has the maximum time work before the sun hits it. I'd also recommend putting in a couple of boxes of borax, first, to raise the pH a bit more (you reported 7.6).

You can use an OTO kit to monitor it. After the initial dose, it will probably give a dark orange brown results (~70 ppm). You do NOT want to swim in this till it drops to dark yellow, unless you begin adding stabilizer first. It won't hurt YOU, but 30 ppm of free chlorine, with no stabilizer, is a swimsuit killer! AND, 20 ppm of COMBINED chlorine WILL give you a skin rash, etc.

PH isn’t an issue, my PH goes up very quickly. It was 8.0+ before I added the 14 gallons last night. Do I just let it stay high during this chlorination process and then add acid after the CC is down?
Are you suggesting I add 25 more gallons (in addition to the 14 I added already) or 25 gallons total?

If the bucket sample was collected BEFORE you added the 14 gallons, then I'd recommend adding 15 gallons, rather than 25.

If you're pH is already near 8.0, you don't need to boost it.

Just to put some closure to the thread, my CC is gone! I added 14 gallons a day for three days. Then More 871 Reagent came in and I was able to measure the chlorine, FC - 25 and CC - 0. Thanks for the support.

Good news! Thanks for reporting back in with the results. Now, time to go swimming!

Quote:

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Originally Posted by PoolDoc

I doubt Leslie's has any R0871, though you could certainly check. If it's much of a drive, I'd call first though.

But, you are right about the R0871 -- I had overlooked the fact that we need to warn people that the high chlorine & cc levels experienced during ammonia clean burn through the R0871 in a hurry.

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just reading through some threads...

FYI - i went through one bottle of R-0871 real quick during the algae clean up. im also going through R-0013 ( almost ran out ) since i have high CYA and am draining/filling/testing every few days untill i get to an acceptable level. i was able to pick up R-0871 at pinch a penny ( .75oz ) and R-0013 ( 2oz ) at leslies. i doesnt hurt to give them a call to see if they have it.

congrats on getting cleaned up clearly!