Why Your Chlorine Disappears Overnight

Show Notes

Chlorine that keeps crashing to zero can make you feel like you’re doing everything “by the book” and still losing. We dig into the real-world reasons pools won’t hold free chlorine in summer, when water temps climb, the UV index spikes, and normal dosing routines suddenly stop working. I share what I’ve seen across years in the field, including why a pool can chew through a gallon of liquid chlorine a day and still test empty, even with a CYA level that looks totally fine.

We get practical about cyanuric acid (CYA) from both ends: how low CYA leaves your chlorine exposed to fast sunlight burnoff, and how high CYA can make chlorine less effective even when you’re reading 8 to 9 ppm. I explain the 7.5% free chlorine to CYA rule, what a workable “sweet spot” looks like for outdoor pools, and why you sometimes have to bend your targets to match brutal heat waves.

Then we zoom out to the other big culprits: underdosing based on 10,000-gallon labels, algae that creates a vicious demand cycle, phosphates that feed growth, and certain stain removers or sequestering agents that can wipe out chlorine if you’re not careful. We also cover circulation and variable speed pump runtime, because chemicals can’t work well if they never fully mix and dead zones keep forming.

If you want fewer chlorine surprises and a clearer plan for pool maintenance, listen through and put these checkpoints to work. Subscribe, share this with a pool owner who’s stuck, and leave a review with the problem you’re fighting right now.

We break down why a pool can burn through chlorine even when your numbers look “right,” especially during brutal summer heat and high UV days. We walk through CYA balance, correct dosing, algae pressure, phosphates, product side effects, and why pump runtime can make or break chlorine stability.
• heat and UV driving rapid free chlorine loss even with decent CYA
• low CYA leaving most of a big chlorine dose unprotected
• high CYA making chlorine less effective and pushing higher targets
• using the 7.5% free chlorine to CYA rule
• underdosing from 10,000-gallon label math and why calculators matter
• algae creating a downward cycle of demand, dead algae, and dirty filters
• aggressive algae response, including higher shock levels and filter cleaning
• phosphates as algae food and when to treat based on test results
• stain removers and other products that can zero out chlorine
• longer pump runtime improving circulation and reducing dead spots
Join the pool guy coaching program. Learn more at swimming poollearning.com. If you're interested in the coaching program that I offer, you can learn more at poolguidecoaching.com.

Send us Fan Mail

Support the Pool Guy Podcast Show Sponsors! 

HASA 
https://bit.ly/HASA

The Bottom Feeder. Save $100 with Code: DVB100
https://store.thebottomfeeder.com/

Try Skimmer FREE for 30 days:
https://getskimmer.com/poolguy 

Get UPA Liability Insurance $64 a month! https://forms.gle/F9YoTWNQ8WnvT4QBA

Pool Guy Coaching: https://bit.ly/40wFE6y

Support the show

Thanks for listening, and I hope you find the Podcast helpful! For other free resources to further help you:
Visit my Website: https://www.swimmingpoollearning.com
Watch on YouTube: https://www.youtube.com/@SPL
Podcast Site: https://the-pool-guy-podcast-show.onpodium.com/

UPA General Liability Insurance Application: https://forms.gle/F9YoTWNQ8WnvT4QBA

Pool Guy Coaching Group

Join an exclusive network of Pool Service Technicians to access the industry’s leading commercial general liability insurance program. Protect your business.

Premium is $64 per month per member (additional $40 for employees and ICs)

$59 per month for Pool Guy coaching Members - join here! https://www.patreon.com/poolguycoaching

Limits are $1,000,000 in occurrence and $2,000,000 in the aggregate - Per member limits

     [ $1,000,000 per occurrence and $4,000,000 aggregate available for $75 per month ]

$50,000 in HazMat Coverage - clean up on-site or over-the-road

Acid Wash Coverage - Full Limits