Free Chlorine ZERO

[mizzouguy]

Okay, neighbor having trouble this year pool has been cloudy for 3 weeks since opening. Pool is cloudy, these were test results:
Stabilizer-40
FC-0
CC-around 4
PH 7.8
Alk 140

Added shock yesterday to try to get to 10ppm checked today and 0 on FC. Went to store and added 13 gallons of 6% chlorine. Checked free chlorine 2 hours later and it is still Zero. How is this possible? The CC is around 2 now.

47,000 gallon liner pool, sand filter.

Any ideas why I can't get the FC chlorine to register.....my pool is registering fine, so I know it's not the test kit. He did take pool water to the store yesterday and they also had zero on the free chlorine.

Is 2 hours long enough to wait?
Is someting really eating the chloring up that fast?
One last thing he did that the pool store mentioned was to Floc....I've never heard of it so I don't know exactly what that is even though he explained it to me. He did that several days ago and didn't help.

thanks for any help!

[waste]

Good to see you again Mizzouguy:) It's possible that whatever is in the water is 'eating' the chlorine - the cc is coming down, so you know that what you are adding is doing SOMETHING;) Keep with the dosing you are doing and have a big bottle of POP (pool owner patience) on hand and all will be fine!

[mizzouguy]

Pool is back to normal after the 3rd day of shocking, the CC was barely showing up at the start of the 3rd shock. 24 gallons of bleach and a bucket of shock all together. Wow, I wonder what the heck was eating the chlorine so quickly???

Anyway, I figured it would work eventually....but I was worried about how fast the chlorine was disappearing! As you said, patience!

thanks!

[chem geek]

I suspect that some of your CYA was consumed by soil bacteria that got into the pool, especially if the pool was "let go" over the winter. Such bacteria convert CYA into ammonia and it takes a lot of chlorine to get rid of ammonia and initially it will increase CC levels with FC registering zero (which is what you saw). In the future, you can buy an inexpensive ammonia test from a pet/fish/aquarium store and figure that you'll need to add a cumulative FC that is 10x the amount of ammonia (measured as ppm Nitrogen).

Richard