Algae every week even though the test kit shows plenty of chlorine? That headache usually isn’t bad luck, it’s bad math. We dig into the most common rookie mistakes new pool service pros make and show the chemistry behind why a pool can read “sanitized” while algae still wins. The big unlock is understanding cyanuric acid (CYA) and how it binds most of the chlorine in the water, leaving only a small active portion available to kill algae. 

From there, we make the fix practical: stop guessing and start targeting free chlorine based on your stabilizer level. We walk through the easy field rule that free chlorine should sit around 7.5% of CYA, plus how adding borates at about 50 ppm can lower that requirement to roughly 5% in many pools. If you’re servicing trichlor pools with high CYA, this framework explains exactly why “6 ppm is high” can still be nowhere near enough. 

We also shift from pure chemistry to water balance and operations. We talk about the Langelier Saturation Index (LSI), what it’s designed to predict (scale forming vs corrosive water), and why “balanced” isn’t the same as “stable” when alkalinity and pH are constantly drifting. Then we hit a nuts-and-bolts issue that ruins otherwise good chemistry: filtration runtime. We explain turnovers, why one turnover only filters about 65%, why three turnovers is a smart target, and how low circulation creates dead zones where algae can grow. 

If you want to tighten up your pool maintenance results, reduce call-backs, and run a more predictable pool service business, listen through and take notes. For more training, visit swimmingpoollearning.com and check out PoolGuyCoaching.com, then subscribe, share the show with a tech who needs it, and leave a review so more service pros can find it.

We break down the most common rookie mistakes that keep new pool service pros stuck in recurring algae, cloudy water, and constant chemical chasing. We show how to set smarter chlorine targets using the cyanuric acid ratio, when borates change the math, why LSI can mislead if you ignore stability, and how pump runtime and turnovers make or break circulation.  
• misunderstanding how high cyanuric acid weakens effective chlorine  
• using the 7.5% of CYA free chlorine target  
• lowering the chlorine requirement with 50 ppm borates  
• why “2 to 4 ppm chlorine” can fail for algae prevention  
• what LSI predicts and what it does not  
• choosing target ranges to make water stable week to week  
• calculating turnovers from pool volume and flow rate  
• why short runtimes create dead spots and let algae take hold  

Learn more at swimming poollearning.com.  
If you're looking for other podcasts, just go to my website, swimming for learning.com.  
And if you're interested in the coaching program, you can learn more at PoolGuyCoaching.com.  

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