FC level not dropping when trying to shock

[dlwxman]

Pool very green. I have studied Pool School and I think I understand all the concepts. I ordered and received the TF test kit.
My CYA was nearly zero so I added enough to get it to 40. I left town for a few days while the CYA dissolved. This morning I tested
and CYA was 40-45 which calls for about 16ppm shock level. I added 4 jugs of bleach (8.25% at 121oz per jug) according to the Pool Calculator. I waited half an hour and tested FC but still 16.5. I waited another half hour and still 16.5. Why isn't it dropping?

 

[Bama Rambler]

Is your pool clear green or cloudy green?

Did you run an OCLT to determine if you had something growing?

 

[dlwxman]

OK. I thought I had read everything in triplicate but missed the OCLT part. Pool is cloudy green...can just make out the top of the light.

 

[Bama Rambler]

That's ok, since it's cloudy green that indicates the need to shock. Wait till last thing to run the OCLT.

Check the FC again in about an hour and see if it's dropped. It may not be consuming the FC very fast.

 

[dlwxman]

OK...I did study about the overnite test earlier and understand. Just started the process this morning. Added bleach at 9:30am. Tested at 10am and FC was 16.5. Tested again at 1030am...still 16.5. Now just tested at 11:15am and it's now 15.5.

 

[Bama Rambler]

Just keep checking it every hour or two and bring it back to about 16.

 

[dlwxman]

While I'm waiting to test FC again, I have another question. Is there a recommended method of adding bleach to the pool? I started by pouring a jug around the edge, then another jug at arm's length then poured the other two jugs into a bucket and spread across the middle of the pool. How long does it take for the bleach to become evenly distributed throughout the pool?

 

[Bama Rambler]

You should pour it slowly in front of a running return. If you do that it takes about 30 minutes to become completely integrated in the pool water. It's probably faster than that, but 30 minutes makes sure it's enough time.

 

[dlwxman]

Running return would be the skimmer or the bottom drains?

 

[Bama Rambler]

Returns are jets where the water is flowing out into the pool (i.e. returning to the pool from the pump).

 

[dlwxman]

OK. That makes sense. Thanks!

 

[dlwxman]

Two tests in a row and the FC dropped to 13. May be from sunlight but have had mostly clouds so far. I guess the UV probably penetrates the clouds anyway. Anyway I'm now in the process of maintaining shock level.

 

[dlwxman]

Is it abnormal for my FC level to be dropping only to the 13-15 range after testing and adding bleach every hour for the last 9 hours? No FC change on a couple of them. My shock level is 16 and I've been padding it to 18. Not seeing any improvement yet. Too early?

 

[jblizzle]

You need POP: Pool Owner Patience.

Just be happy you are not having to use gallons of bleach every hour.

 

[Zadd]

POP absolutely but you are on top of it. The more you keep it at 16 or slightly over the faster you will see improvement. Keep it up.

 

[dlwxman]

Thanks to all! I've got POP but, being new to this, I just didn't know what to expect.

 

[dlwxman]

Is the CYA test valid under high FC levels? Maybe I should re-check it? Just read about re-mixing a few times and checking the levels. Also I did it indoors rather than outdoors.

 

[jblizzle]

The CYA test is not affected by the FC.

You can pour the mixture back and forth a few times to see if you get the same answer ... and outside with your back to the sun is the proper lighting.

 

[GuinnessPhish]

Is the CYA test valid under high FC levels? Maybe I should re-check it? Just read about re-mixing a few times and checking the levels. Also I did it indoors rather than outdoors.

The recommended way to test CYA is outdoors, with sun shining, back to the sun, test tube at waist level.

 

[yeggim]

Is the CYA test valid under high FC levels? Maybe I should re-check it? Just read about re-mixing a few times and checking the levels. Also I did it indoors rather than outdoors.

CYA testing is not affected by Chlorine levels. Proper lighting is essential. Outdoors when the sun is high is best. Turn your back to the sun so the vial is shaded and hold at waist level looking straight down at the dot as you pour. Clouds, sun down low will give you different results as will testing indoors.