Chlorine Loss?!?!

[s_vidden]

demilio56,
Just want to double check that you are aware that FC does not deplete linearly. Extreme amounts of FC will deplete much quicker than FC several points above your target. It is not a X amount of ppm loss per hour. With CYA of 50 and FC above 44, you will experience exponential loss in FC compared to FC just below the recommend shock level.

You also mentioned your not entirely confident in your last CYA test. Have you tested recently? I like to test 3 times in one session if I am unsure of my findings and take the average. Just dump the solution back into the droplet container and retest again. Also, visit the Pool School page if you are not sure how to accurate test CYA. I place my back towards the sun around 10-11am on weekends and hold the test vial at waste height and proceed.

 

[demilio56]

Vidden,
I was NOT aware that FC loss was not linear. Thanks for that lesson!

When I say I was not confident in my CYA test, I meant I was questioning if my reagent was bad. My latest CYA test was this week. I've never liked the test because of the subjectivity but I do always do it in full sun, with sun to my back, waist height, etc. I never thought to retest and take averages...I will definitely start doing that.

Thanks again. This was all great information.

 

[demilio56]

6:30 a.m.: 17.5 ppm fc

to 12:30 p.m.: 15 ppm fc

Things look to be slowing down. It's still a decent amount of fc drop for a morning with zero use but based on my newfound knowledge from s_vidden above, perhaps that is going to continue to slow down as the fc level drops to within normal range. The pool figures to get heavy use this evening and tomorrow so I'll monitor very closely. I've met the three SLAM criteria and will check OCLT the next couple nights to be sure. I'll very carefully and repeatedly be testing my CYA once my new reagent comes on Monday.

 

[s_vidden]

6:30 a.m.: 17.5 ppm fc

to 12:30 p.m.: 15 ppm fc

Things look to be slowing down. It's still a decent amount of fc drop for a morning with zero use but based on my newfound knowledge from s_vidden above, perhaps that is going to continue to slow down as the fc level drops to within normal range. The pool figures to get heavy use this evening and tomorrow so I'll monitor very closely. I've met the three SLAM criteria and will check OCLT the next couple nights to be sure. I'll very carefully and repeatedly be testing my CYA once my new reagent comes on Monday.

I think your heading down the right track.

 

[jstblush]

One thing I want to mention is the way you hold the tube. If you hold it with only your thumb and index finger I have noticed the number is different than if you put your hand around the whole tube. My husband used to put his hand around the whole tube and the number was quite different from the way I do it. I use the thumb and index to hold the tube. It lets more light into the tube and I believe this is the correct way to hold it. Someone can correct me if I'm wrong. But just thought I'd mention it.
Good luck.
Sherry

 

[s_vidden]

One thing I want to mention is the way you hold the tube. If you hold it with only your thumb and index finger I have noticed the number is different than if you put your hand around the whole tube. My husband used to put his hand around the whole tube and the number was quite different from the way I do it. I use the thumb and index to hold the tube. It lets more light into the tube and I believe this is the correct way to hold it. Someone can correct me if I'm wrong. But just thought I'd mention it.
Good luck.
Sherry

I agree Sherry.

 

[mknauss]

Thank you all for helping the OP. It takes a forum of people!

If FC consumption is still high, add 10 ppm of CYA. What you have added this year so far as you posted was about 35 ppm.

Main thing is, swim! That is what a pool is for.

It is safe to swim in a pool as long as FC is above minimum and at or below SLAM level. You must also be able to see the bottom of the pool in the deep end.