Unexpectedly high FCL

seanauld

Member
Aug 4, 2021
11
halifax, nova scotia, Canada
Pool Size
430
Surface
Fiberglass
Chlorine
Liquid Chlorine
Good Evening,
Switched from Dichlor to bleach today given the information I received from reading the numerous posts related to the negative effects of CYA on the FCL.
Today took the initial measurement using Taylor FAS DPD kit , 1 PPM FCl, less than .5 CCl, AL, pH, CH within specs and CYA at 50 ( i was using dichlor for 2 1/2 weeks).

Pool math indicated to add 2.7 oz to bring FCL to 5 PPM. Added the liquid chlorine ( 10.3 % ) , circulated for 20 minutes with pumps in and then took reading 10 minutes later ....13 FCL with essentially zero CChl.

What have I done wrong?

Thank you
Sean
 

Newdude

Gold Supporter
TFP Guide
Jun 16, 2019
10,352
NY
What have I done wrong?
No idea. I ran your 430 gallons in my pool math and I get 2.8 oz for 5ppm. If you fell short than the bleach was old/weak……. But more than double ??? 🤷‍♂️

What are you measuring with ? Any chance you used a half cup and not a quarter ?
 

seanauld

Member
Aug 4, 2021
11
halifax, nova scotia, Canada
Pool Size
430
Surface
Fiberglass
Chlorine
Liquid Chlorine
Thanks for your reply. I really don't think it's possible, I am using a mason jar that I poured water into using a shot glass for each oz.

That said anything is possible, I'll double check next time, probable try half and see what I get. I thought I might have done something wrong rather than a simple measuring error.

Thanks
Sean Auldn
did you switch from 10ml sample to 25 ml sample for one test or change the 1 drop = ???ppm formula
Thank you, I only use the 10 ml, .5 ppm as I went through too much of the 871 reagent initially, and Taylor reagents, especially the powder and 871 liquid are crazy expensive here in C.anada

Appreciate your reply. I'll double confirm my next addition and see if I get a different result.

Thanks
Sean
 

jseyfert3

Silver Supporter
Bronze Supporter
TFP Guide
Oct 20, 2017
1,763
Southern WI
Pool Size
15000
Surface
Vinyl
Chlorine
Liquid Chlorine
Thanks for your reply. I really don't think it's possible, I am using a mason jar that I poured water into using a shot glass for each oz.
You are using a shot glass to measure each oz of bleach? Have you measured the shot glass? I grabbed a random shot glass we have here and filled to the brim is held 2.0 US fluid oz when measured by pouring into the graduated 8 oz measuring container I use for measuring bleach and acid for my hot tub.
 

Mdragger88

Bronze Supporter
Jun 1, 2018
2,733
Hernando, Ms
Pool Size
26000
Surface
Vinyl
Chlorine
Salt Water Generator
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I’m patiently awaiting the conclusion!
 
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seanauld

Member
Aug 4, 2021
11
halifax, nova scotia, Canada
Pool Size
430
Surface
Fiberglass
Chlorine
Liquid Chlorine
Initiating Research...
...


I don't know what is responsible for this evil, but I know darn well that I'm blaming the metric system!
Thanks folks, the shot glass actually had 1 oz, 1 1/2 oz markings so reasonably sure I was accurate , though I have to admit that since I passed 50 years…..human error is starting to be the most frequent causal factor.

Will let you know the results of the second try, levels have come down to 8 ppm over the last few hours.

thanks
sean
 

seanauld

Member
Aug 4, 2021
11
halifax, nova scotia, Canada
Pool Size
430
Surface
Fiberglass
Chlorine
Liquid Chlorine
Thanks very much will do !
Sean
Good Morning All,


Sincere apologies , waited for the FCl to drop to .5 and then added first about oz. Which brought it upto 2.5 ppm and than added another oz and which saw it raised to 4.5 ppm...obviously human error the first time.

One quick question, how much water should I dilute the 2 oz. of liquid chlorine in prior to adding to the hotub, would a 1 gallon bucket be sufficient dilution prior to adding ?

Thanks
Sean
 

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