high CYA means I need high level of chlorine. Is it safe to swim?

[Kjrivalsi]

First, I must say I love this website.
I recently switched to liquid chlorine and have been testing my water with TF-100 daily.
I think I have it under control and the knowledge gained is empowering.

Question:
My CYA is ~75 ( I pumped out about 10,000 gallons of water and refilled to get to this level).
With a CYA of ~75, my target Free Chlorine level is "6 - 11" (PoolMath) but I am trying to maintain ~9.
Pool looks great but....is this level of chlorine (~9) safe to swim in?

thanks in advance, Ken

 

[PoolGate]

Yes perfectly safe.

 

[Newdude]

Any level on the FC/CYA Levels is equal.
You are safe to swim between minimum and SLAM.

Don't get tripped up by poolmath. The 6-11 reccomended range is minimim to high target. Pool Math is assuming you are testing to see how much to add today. At that point, having 7 FC is fine. That should be tomorrow's *end* point, not today's start point. 11 is today's start point.

 

[Oly]

75ppm CYA is not on your, our test scale. Because the scale is logarithmic best practice is to round up. You may get a monthly decline in CYA so test again in 30 days or so.

 

[Kjrivalsi]

Any level on the FC/CYA Levels is equal.
You are safe to swim between minimum and SLAM.

Don't get tripped up by poolmath. The 6-11 reccomended range is minimim to high target. Pool Math is assuming you are testing to see how much to add today. At that point, having 7 FC is fine. That should be tomorrow's *end* point, not today's start point. 11 is today's start point.

Thanks for the PoolMath range explanation. Makes sense now.

 

[Newdude]

Also. Always round up. As such, you only need to test the 10s because all the 70s except 70 will be an 80.(etc) Call yours 80 and switch to it on the chart and poolmath.

 

[SoDel]

75ppm CYA is not on your, our test scale. Because the scale is logarithmic best practice is to round up. You may get a monthly decline in CYA so test again in 30 days or so.

https://www.cmu.edu/biolphys/deserno/pdf/log_interpol.pdf

(I’m sorry, just being a wiseazz for a second )

 

[Oly]

Measure it with a micrometer, mark it with a grease pencil then cut it with an axe.
It gets you there but recognize the weak links, the assumptions and when to keep it simple but safe.