Chlorine loss during the day.

[JLP3]

Is it normal to lose 5.5ppm FC during a hot day? I have 0 shade, 96°, uv index of 7. Started at 8.5 FC and dropped to 3. Thanks.

 

[YippeeSkippy]

How much CYA do you have in the water? A loss of anything between 2-4ppm is understandable.
What are your test results using a approved test kit?
FC
CC
pH
TA
CH
CYA

Maddie

 

[Newdude]

It is very possible. Many in the hot climates raise their CYA 10 at a time and road test the new level when the FC loss seems excessive.

Overnight Chlorine Loss Test before raising the CYA though because your SLAM target goes up 4ppm for every 10 CYA.

 

[Oly]

Any bodys using the pool prior to testing the FC drop? Do an
Overnight Chlorine Loss Test to be sure and if you pass ok then add 10ppm of CYA to your pool to raise it to 50ppm then after several days test your daily FC loss again.

 

[mknauss]

Poolmath shows a CYA of 40. Raise it to 50. As long as you have no algae.

 

[JLP3]

These readings were from this morning.

FC 8.5
CYA 40 (Probably closer to 37)
PH 7.0
TA 9O
CH 250

I just finished slam 2 nights ago, pool is absolutely gorgeous, met all criteria to finish slam with flying colors including the oclt (did not lose any overnight). The only thing I have done since ending the slam is add some calcium hardness increaser. So I got up before work this morning and recorded levels so I would get an idea of how much uv loss I was gonna have daily. Thank you all. Nobody's used the pool at all yet. Thanks to all.

 

[mknauss]

Be aware that for some reason, adding calcium chloride tends to consume some FC.

 

[JLP3]

I did not know that. So, since I added calcium chloride within the last 24 hours, should I wait and retest the UV loss before raising Cya? Or just go ahead and adjust the cya to 50 anyway? Thankyou....

 

[mknauss]

You can raise the CYA.

 

[JLP3]

Thank you sir

 

[YippeeSkippy]

Just an FYI- Vinyl pools don't need any calcium.

Maddie

 

[JLP3]

Man, I learn so much on this site. Thanks.