FC usage during the summer in Phoenix

[vaalpens]

I started using the TFPC methodology in September 2016 and has been very happy with the results. Since I started following the methodology after the summer, I wasn't sure how things would change during the summer time.

Starting Sep/Oct 2016 I was using around 12oz of 10% daily on average. This summer after it started heating up I did some more regular testing and it seemed that my FC depletion has increased a lot. Following are my test results over 2 nights:

CYA: Around 65
CC: Always 0 or .5
Water is very clear.
6/11 @ 20:00: FC: 9.5
6/12 @ 07:00: FC: 9 (loss of .5. the sun was out with limited sun on pool)
6/12 @ 19:00: FC: 4 (loss of 5 during the day)
Added 48oz of 10%
6/12 @ 20:00: FC: 8.5
6/13 @ 06:30: FC: 8 (loss of .5. the sun was out with limited sun on pool)
6/13 @ 12:00: FC: 4.5 (loss of 3.5 about half the day during full sun)

I'm not sure if the .5 loss over night means a slam is needed, but it seems the a loss of 5 during the day seems high, but this is the first summer that I actually used a quality kit to test my pool.

I would appreciate it if you can comment on what to expect at our current temperatures and if a slam is necessary.

 

[JoyfulNoise]

A clean and clear pool will lose 2-4ppm in a NORMAL climate. Phoenix, AZ is NOT your normal climate.

You may need to bump up your CYA to a higher level to reduce UV loss. We are on the middle of the hottest time of the year (temps > 110F) and your water is going to drink chlorine like Gatorade.

 

[vaalpens]

A clean and clear pool will lose 2-4ppm in a NORMAL climate. Phoenix, AZ is NOT your normal climate.

You may need to bump up your CYA to a higher level to reduce UV loss. We are on the middle of the hottest time of the year (temps > 110F) and your water is going to drink chlorine like Gatorade.

Thanks for the confirmation about the chlorine use. My CYA has been holding steady between 60 and 70 (sometimes difficult to read with old eyes) so I have not tried to increase it. I'll just keep an eye on it to ensure I don't suddenly start losing CYA.

Just a question regarding CYA. If the CYA increases, doesn't that mean I need to keep the FC at a higher level?

 

[jblizzle]

Yes, higher CYA levels require higher FC levels, according to the [FC/CYA][/FC/CYA].
But, higher CYA protect a higher % of the FC from the sun, so your daily chlorine additions should be a little less.

 

[vaalpens]

Yes, higher CYA levels require higher FC levels, according to the [FC/CYA][/FC/CYA].
But, higher CYA protect a higher % of the FC from the sun, so your daily chlorine additions should be a little less.

Thanks for the additional information. My plan actually was to lower the CYA to around 50, but for now it seems I need to just hold off for now until we are through the worst of the summer.

How do you determine what the best CYA level is for the pool. With a higher CYA I need to maintain a higher FC, but then my daily consumption of FC should be less.

 

[jblizzle]

There is no perfect level. The higher the cya the less your daily loss should be. the only time that really becomes a problem is if you need to follow the slam process.