trouble passing OCLT--please help

curleah

Active member
Feb 23, 2011
26
Northeast OK
I have been using the BBB method for several years now and thought opening this year would be a piece of cake. Our water was not green when I began. Dirty, yes, but nothing like the first year I sought out this forum. We've had so much rain here in OK that I have had to empty water out of our pool 2-3 times and a bunch of it. I feel like it's one step forward and 2 back. My FC results are all over the place. Even back to back tests. Is it possible that my test kit is old? Do things expire?

We are on the 3rd week of slamming. Water has been clear for the past week and a half or so. My results just now:
FC-15
CC-1
TC-16
TA-90
CH-110
PH-7.6
CYA-20-30 (this test is hard for me to read, depending on lighting it could be somewhere in between)

I had started out with a CYA of 40 with the slamming process. We had floated chlorine tablets most of the winter. With all the rain and having to empty water, CYA has dropped. I had also dropped the PH to 7.2 before slamming.

Last evening I tested the FC. It was at 6. I added 3 jugs of bleach to bring it up to 15. I tested after an hour, before bed and the FC was 22.5! How does that happen? Tested again first thing this morning at 6:30am and it was 17.5. So, I am still dropping substantially overnight. Tested again at 10:30am and FC is 15.

A few days ago my CC was only .5. Now it's to 1. I have never seen results all over the place like this before and I am not sure what to do. We brushed the pool Saturday and Sunday (that's not the only times) and I plan to brush again today.

(25,000 gallon above ground pool with sand filter)
NE OK
 

domct203

Bronze Supporter
LifeTime Supporter
TFP Guide
Jun 3, 2015
3,959
CT
Sorry to hear that the SLAM has been difficult for you. With the FC loss you are experiencing, as well as the CC of 1ppm, there must still be some algae hiding somewhere.....

Is the ladder in the pool? Are there any lights or other areas that could hide algae? Check the seams of the liner, if they overlap algae can hide in there.

Stick with it. While all SLAMs are different, one thing remains the same, chlorine is the answer.

I just double checked that 96oz of 8.25% laundry bleach will add 2.5ppm of FC to your pool, so your 3 jugs of bleach would have added 7.5ppm to the 6ppm for a total of 13.5ppm. If you got 22.5ppm there are some testing errors here, either in the starting ppm, or the ending ppm. It would have taken almost 7 jugs of bleach to go from 6ppm to 22.5ppm.

If you were using 128oz (gallon) jugs of 12.5%, three of them would bring the pool from 6ppm to 21ppm.
 

curleah

Active member
Feb 23, 2011
26
Northeast OK
Thank you for your response. No, we have not put the steps in the pool, yet. Like I said, I have been doing this for several years with this test kit and this has never happened before. I will keep scrubbing and slamming.
I did order some new testing supplies.
 

Richard320

TFP Expert
LifeTime Supporter
Jan 6, 2010
20,403
San Dimas, CA (LA County)
I recall a couple years ago that someone else had this same problem. Turned out it was a dirty test vial creating CC during the test. Maybe you should try scrubbing the thing clean and really bleaching it good and let it dry completely before you try the OCLT again. Or switch test vials.
 

curleah

Active member
Feb 23, 2011
26
Northeast OK
Thanks everyone! The pool finally passed the OCLT! I think it may have been a combination of a few things. I upped the CYA to 40 and ordered some new testing supplies. I am now getting consistent results. I think my testing supplies were outdated.
 

atttech-2

Bronze Supporter
TFP Guide
Jul 24, 2015
1,181
Central Valley CA
Turned out it was a dirty test vial creating CC during the test. Maybe you should try scrubbing the thing clean and really bleaching it good and let it dry.
Sounds like problem solved but about cleaning the vial I think it was Dave that mentioned in a post I saw last year to try some MA in the test vial to clean. Couple drops got rid of all the DPD spots and haze like a magic eraser, stuff that I had scrubbed and scrubbed to no avail.
 

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