Can't Lower Cl Level

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C

Cultcab

0
Oct 23, 2016
51
Roseville, CA
I have a 15K gallon in-ground pool and I can't get the Cl level to drop. It's been over 20ppm for about 2 months.

I use 3" tabs in the skimmer and I alternate in with liquid CL about every 3 or 4 applications. I shock the pool with 68% Calcium Hypochlorite about every 2 or 3 weeks during the summer and about once per month in the winter (we're in Northern California, so the winter is short).

I have also been trying to lower my Cyanuric Acid level (I assume that it's tied in with the high Cl) - I've been over 100ppm since August and I've drained my pool down ~6" three times now without any significant reduction.

The rest of the readings are within normal range: pH = 7.6, Alkalinity = 70 - 80, Ca Hardness = 400 - 450.

Besides draining the pool a few more times, is there anything else I should be doing?
 
IF your FC is that high, you're adding too much chlorine to the pool. Simple as that.

Do you test routinely before adding more pucks, powders and liquid chlorine to the system? As weather cools down so does the amount of chlorine one needs. It just isn't burned off/used up as quickly.

Your CYA won't lower if you keep using pucks with yet more CYA in them either.

Please review this --> Pool School - Recommended Pool Chemicals
 
See answer below each applicable statement of yours:

I have a 15K gallon in-ground pool and I can't get the Cl level to drop. It's been over 20ppm for about 2 months.

when you refill your water, have you tested the contents of the water?[/B
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I use 3" tabs in the skimmer and I alternate in with liquid CL about every 3 or 4 applications. I shock the pool with 68% Calcium Hypochlorite about every 2 or 3 weeks during the summer and about once per month in the winter (we're in Northern California, so the winter is short).
To clarify, you have not added ANY CL of any nature for all of Sept & Oct, and in Nov your FC is still 20PPM? Are you still shocking it? If no to either, then either your testing methodology is completely off or someone is adding CL to your pool and you do not know it.

I have also been trying to lower my Cyanuric Acid level (I assume that it's tied in with the high Cl) - I've been over 100ppm since August and I've drained my pool down ~6" three times now without any significant reduction.

Yes, higher CYA PPM readings will certainly require more CL to work the same. As noted, each puck adds about 2-3PPM per puck. As noted, one drain of 3x6" is 18" is way more effective than 3 drains of 6" over time. Your 6" drain offs are recombined w the existing water, which does not have the same impact as diluting 18" at one time.

The rest of the readings are within normal range: pH = 7.6, Alkalinity = 70 - 80, Ca Hardness = 400 - 450.

Besides draining the pool a few more times, is there anything else I should be doing?

Here's a question for you: What have you added to your pool in any form of any kind over the last 2 months? Include water too if drained.

Next, how old is your test kit? Go get a new test kit that tests for FC and pH. then test and tell us. also, use water about 1 ft below the top.

Something is certainly not adding-up correctly. Also, who is maintaining the pool?
 
I tried a "new" Cl kit (DPD Powder and titrating reagent) and got the same results. I think even though both were unopened, they are at least one year old.

I will order new test components and try again.

The CYA tester is fairly new, so I'm assuming that that reading is accurate. Based on the feedback, it sounds like my best course of action is to do a long pool drain (maybe 25%) and then retest.
 

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tstex said:
Pls tell us everything you have added to your pool in the last 2 months????
Click to expand...
This is an extremely important piece of the puzzle. While you may have not added bleach (liquid chlorine), if you continued to shock and or use pucks, you were still adding chlorine.

Even with an indoor pool, I cannot see how the chlorine stayed at the exact same level for 60 days unless some were added.

Is there an inline chlorinator?
 
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