Pool appears balanced but chlorine usage is too high

[Danek]

Hi everyone, first post, thanks too all for the info I have gotten from browsing the forum. I have switched from baquacil to chlorine this year at opening late May. I used granular shock and initially used tricolor tabs once conversion was complete. The problem is my chlorine is being used up quickly and the pool stores were no help. I decided to buy a test kit and do it myself with the BBB method.
i slammed with bleach and have passed the OClt test and my cc is 0, water is clear and still have high chlorine usage. I added cya to get to 50 and borax to adjust ph.

my numbers
cya. 50
ph 7.4
ch. 225
ta. 100
cc 0
FC is initially 6 after 1 bottle of 10%, but in a few hours is gone

i did have some white mold at opening, but changed sand in filter half way through conversion.

ive used great value bleach and pool essentials 10% liquid chlorine

any ideas about the chlorine usage?

Thanks

 

[Texas Splash]

Hello and welcome! I have to say though, something seems odd in your narrative. You mentioned about completing the conversion THEN getting a proper test kit, but without the FAS-DPD to test FC over 10 (15 for the conversion), I'm wondering if the conversion was actually completed properly? Once you can hold the FC of 15 from the conversion THEN change the media (sand), it should be smooth sailing. If you didn't follow the TFP Pool School - Convert Your Baqua Pool to Chlorine steps precisely, it's possible there was some residual baqua goo in the system.

At this point it's almost a non-issue since I assume the sand has been changed and you've added stabilizer. You definitely should not be losing more than 4 ppm of FC in 24 hrs, and you appear to be losing more than that. It's time to so a SLAM Process. Lower your pH just a tad to 7.2 and crank the FC up to "20" (the proper SLAM level for your CYA). Use only regular bleach to increase the FC and maintain it until you pass all 3 SLAM criteria. The SLAM could take a couple days, it could take several days, but it should work. Stay with it and let us know if you have any other questions.

 

[Danek]

The conversion was done with pool store testing. Then I got the test kit and slammed before I had much cya, just 4 from pool store, test kit couldn’t show any with the limitations of the cylinder. I met all 3 criteria but still have high chlorine loss during the day. I did see since posting that previous Cdx use could be a problem interfering with the cya, now at 50. I’m assuming now that it will take a lot of chlorine to get rid of the cdx.

 

[Texas Splash]

The conversion was done with pool store testing. Then I got the test kit and slammed before I had much cya, just 4 from pool store, test kit couldn’t show any with the limitations of the cylinder. I met all 3 criteria but still have high chlorine loss during the day. I did see since posting that previous Cdx use could be a problem interfering with the cya, now at 50. I’m assuming now that it will take a lot of chlorine to get rid of the cdx.

Well, I gotta tell you, I sure wish you would've found us and posted with us before starting the conversion. We definitely would've advised you to wait until you had a TF-100 or Taylor K-2006C so you could test at home frequently and accurately to meet that 15 FC criteria. I have sneaky suspicion some goo might still be present and didn't get completely cleared. I'm going to PM our baqua expert for another opinion though. See what he has to say. Hang tight.

 

[Leebo]

Danek,
Welcome to the forum!!!!!!!


Please forgive me as my brain is somewhat foggy tonight. Up for work at 1:30am and have ran ever since.

So let me make sure I’m understanding. You did the OCLT and lost less than 1ppm FC overnight. Additionally your CC level is zero. Is this all correct?

If so, did you have the pump running during the OCLT?

 

[Danek]

Yes, true, pump runs continuously