What can cause continuous high CC besides algae?

[Kpasciak]

I have been SLAMing my pool for 8 days now because of a reading of CC=1

The water has looked clear the whole time.
CYA between 30-40 (using SLAM value of 16)
I passed the OCLT.
My CC remains stubbornly at 1-1.5.

Filter is running 24/7 and pressure is not rising (staying around 13)
Manually brushing pool
Using vacuum 2x a day

I only used CYA, Bleach, and PH up (and now down)

Is there something else (environmental?) that can mess with the CC test?

We fixed the steps with Bondo, Resin, and Gel Coat before opening.
We live near an international airport and there had been lots of rain prior to the 1st high reading.
Can an issue with the sand filter cause this?

Should I try DE in the filter?

 

[duraleigh]

How many days has the water "looked clear"

How many days since you passed OCLT?

Has the CC test been 1 or more each day since OCLT?

 

[jblizzle]

Is there a cover on the pool?
How are you testing the FC and CC?
Bottle vertical, adding a fully formed drop every 1 second or so and stopping the count when it first goes clear (not counting the fact the sample will turn back to pink if you let it sit there).

 

[Kpasciak]

Water has looked clear the whole time.
I started the SLAM because of the CC reading of 1.

2 nights ago, passed the OCLT
Will repeat test tonight.

Yes, CC has been 1 or more each day (even after OCLT)

No cover on pool (It did not come with one/ we bought this house last year)

Havent seen any dust or algae on the bottom. Nothing blooms when brushed.

Yes- I am testing with bottle vertical, dropping 1 drop at a time until pink disappears.
Then I add 5 drops of reagent #3- turns it pink.
Takes 2 drops to clear the solution again, sometimes 3.

 

[jblizzle]

Given a clear pool and passing the OCLT, I am not sure I would be concerned about a slightly elevated CC enough to actually keep following the SLAM process.

The OCLT tells you there is nothing in the water consuming the FC needing to be eradicated.

You ever use any thing "odd" like non-chlorine shock or algaecides or sequestrants?

 

[Kpasciak]

Thank you for responding

I didn't add anything like that this year.
I did add algaecide and Metal Out last year before figuring out the Trouble Free Pool method.
The pool was drained down to the bottom step in the spring while we repaired the top 2 steps.
The pool was testing fine at first after we added water and opened it up this year.

 

[aussieta]

as jason said dont be too slow when running fc and cc test as it will turn pink in a few seconds one drop per second

 

[Kpasciak]

Passed the OCLT again last night (between 9:40 and 4:15)
FC dropped .5
CC remained 1

I am going to let the FC levels drift down and see what happens.
Still confused as to what is causing the CC.

Thanks everyone!

 

[duraleigh]

Keep your FC levels elevated slightly........maybe 6-8 ppm for another few days.

puzzling, but certainly no reason to stay at SLAM FC. Go swimming and enjoy your pool.

 

[Kpasciak]

That sounds good. Thank you.

 

[SwimAustin]

Yes- I am testing with bottle vertical, dropping 1 drop at a time until pink disappears.

The usual directions here are to add drops until a drop causes no color change, then don't count the last drop. If you stop when the sample turns clear, that's one less drop and so you'll read a higher CC level. That wouldn't entirely explain your reading, but it is something to keep in mind.

 

[buzzard302]

Where do you store your test tube? Years ago, I also got CC readings after 5-6 days of slamming with crystal clear water and no overnight chlorine loss. Turns out the inside of the test tube was dirty. I let some chlorinated water sit in the tube for a few hours and then cleaned the tube out well. Next test, no more CC. Check your test equipment, you may be tricking yourself.

 

[Kpasciak]

I did read that here. I have tried the test both ways. A few weeks ago I passed the CC test, even without the extra drop.
Now, it takes me 2 or 3 drops each time for it to go clear. I fail either way.

I am wondering if somehow reagent 3 got contaminated or stopped working. The other 2 reagents are brand new.

- - - Updated - - -

I will clean the tube well. Maybe that is it? I usually rinse the test tube with tap water and store in on my kitchen counter.
I then rinse it in the pool while I collect a sample with the bottle.

 

[Kpasciak]

Holy cow! It was the darn test tube! Or at least it seems it was.
I washed everything with really hot water and wiped out the inside with paper towel.
Dipped everything in the pool and repeated the test several times.
CC is now below .5!

I will test again in an hour. Hopefully this was the missing piece.

Thank you so much.
I was starting to go a bit crazy.

Also FC held at 9 1/2 ppm from 10:00 PM until 8:30 AM
Crossing my fingers that I can move forward

 

[Kpasciak]

Just ran a set of tests and the CC is still gone!

FC=9 1/2
CC=0
Alk=90
PH=7.7

I will knock the PH down a bit, but everything else looks good
I will test CYA when we have some sun just to check it again and then get back to keeping a FC in a good range.

 

[jblizzle]

Glad you got it figured out. I will have to keep this in mind.

 

[Kpasciak]

Everything is testing great now and since the CYA is holding the chlorine, I haven't had to add any more bleach yet!

So glad to have an answer!

 

[eripaulie]

I had the same problem a few years ago, cleaning the chlorine test tube worked. It drove me crazy until I figured that out. Now I just get a new tube every year.

 

[buzzard302]

I have posted this solution multiple times over the years. It seems to be common enough that I am surprised it is not talked about more. Glad you found the answer.