FC is not raised as much as it should

[mmdhar]

My last test numbers...
FC- 1.0
C - 0
PH - 7.6
TA - 100
CH - 650
CYA - 60

My pool size is 13650 gallons. PoolCalculator says add 102 oz of chlorine to bring the FC up to 7. I added 128 oz (1 jug) of Liquid chlorine that I bought at NPS store. As per Pool calculator, FC should raise to > 7

But, I tested my water after running the pump for 30 mins after adding the chlorine. FC was 5.5.

Any ideas on why FC was not raised to > 7? I noticed this a few weeks too. Then I was buying liquid chlorine at Lowes. I thought Lowes has old stock and chlorine must have lost its strength. I checked with NPS associate and he said they get a new pallette every week. So, it can't be too old.

Thanks!

 

[jblizzle]

What was your CC for the 2nd test?

Could be that your pool is bigger than you think or the bleach may have been weaker than you thing or there is something in your pool consuming the FC.

You should be checking the date code if you are buying the HD or Lowes where they store it outside. Check out the chart here: http://www.troublefreepool.com/thre...ge-temperature?p=725315&viewfull=1#post725315

If it started at 12.5% and was stored outside in AZ, within a week it could be down around 10% ... so the 10% that they sell could be down to around 8% in a week since it is store out in the heat.

 

[JVTrain]

With your FC being that low with your current CYA level, you could easily have live algae or bacteria in your pool. Those could consume some of that FC almost immediately.

Also, how is your pool volume calculated?

 

[mmdhar]

I didn't check CC the second time. I found the pool volume in the documents I got from when the pool was built.

But, what jblizzle mentioned must be the reason. I have been storing my chlorine in the garage. It has been 2 weeks since I bought it. I didn't realize it would lose its strength so fast. Ok, I'll search for storage options.

Thanks a lot!