Kept FC overnight, but still consuming a lot of chlorine...

[ovranalyzr]

I am confused. I have been following the BBB method for about 2 years now with great results. My water is crystal clear. I have been maintaining shock level for about a week or so and have not lost any FC overnight. However, I am still consuming a lot of chlorine throughout the day. I have read that 3-4 ppm of loss is normal. I have started with 7-8 ppm in the morning and by 7:00 PM or so I will have 0 for the past 2 days.

If anyone can shed any light on this it would be greatly appreciated. My current numbers are listed below. BTW, my CYA test can't be accurate because a month ago it tested around 50 and I have not drained any water. I ordered refills and something has to be wrong. Thanks as always.

FC - 0 (was 7.5 this morning)
CC - 0
PH - 7.8
TA - 100
CH - 80
CYA - 0 (with new refill, tested at 50 a month ago)

 

[duraleigh]

Two things consume chlorine.....

1. Sunlight (UV)

2. Algae and other organics in the pool

If your water is crystal clear and you lose no FC in the nighttime, sunlight is all that's left.

Somehow the CYA must be gone from your pool.

 

[ovranalyzr]

Let me ask this... would either of these items have anything to do with this.

1) I am pretty certain the sand in my filter needs changing. I wouldn't think this would matter since no FC is consumed at night, but I could be wrong.

2) Does it matter how long I am running my pump during the day or night? While shocking I ran it 24/7. I have now changed it to about 10 hrs a day, but the results didn't vary.

 

[duraleigh]

No, both are irrelevant to FC loss.

 

[ovranalyzr]

That would make sense as to why I can't keep chlorine during the daytime. This begs the question, how in the world did my CYA disappear? I thought that was only possible if you drained water from the pool and refilled with water with no CYA.

I tested the CYA twice to make sure I was testing it properly and both times there was nothing. The water wasn't cloudy at all. Is there any way to verify this is correct without ordering another refill?

 

[chem geek]

Was there any point in time when the FC dropped to zero for more than one day? If so, then bacteria could have converted the CYA to ammonia, but I would have expected that to result in a very large chlorine demand. It only takes a few days for the bacteria to do this (I had this happen in my own pool earlier this season).

I would say it's very likely your CYA is near zero given the rapid FC drop during the day and the CYA test being clear.

 

[iwannatfp]

last year i closed my pool with CYA of ~40.
this year i opened and every day i lost all of the chlorine i was adding.
checked CYA and it was 0 !
slowly brought it up again using old pucks.

until the CYA was above 20, i lost every bit of chlorine i added during the day

 

[duraleigh]

Is there any way to verify this is correct without ordering another refill?

Take a sample to a pool store. Their testing is often innaccurate, but they should be able to confirm a zero reading.

 

[ovranalyzr]

I would have to say that yes, the FC probably dropped to 0 for at least a day or two. I don't think I was watching it as closely as maybe I should have. I didn't expect that much of a drop in FC!

What is the best way to get the CYA back up? Balancer or maybe some of the old pucks in the chlorinator.

 

[frustratedpoolmom]

The best way would be to go buy some CYA/"Stabilizer" and add enough to raise your CYA level to 30. Because it's possible you have less than 20, which won't register on the view tube. You don't want to overshoot. Walmart and similar stores with pool departments also sell it. Using pucks would take too long. If your FC is holding overnight, I doubt you have an ammonia issue.

 

[ovranalyzr]

Thanks to everyone for the replies. I went to Wally World today and it was my luck that they were out of stabilizer. I went ahead and bought some pucks just to get me by until I find the stabilizer. Worst case it will not add enough CYA, but any at this point will help. Thanks again.