Why does my pool turn green overnight during an Austin heatwave?

“July in Austin is a race between your chlorine and the sun. The sun usually wins.”

It’s a frustrating experience: your pool was crystal clear on Saturday, but by Sunday evening, it looks like a swamp. In Austin, the “Heat Dome” doesn’t just make you miserable; it creates the perfect breeding ground for algae.

The Science of the Green

When water temperatures exceed 90°F, algae growth accelerates exponentially. At the same time, UV rays from the intense Texas sun can destroy 90% of your chlorine in just two hours if your water isn’t properly “stabilized.”

Expert Tips for 100°+ Weeks:

1. Check Your CYA (Stabilizer): Maintain Cyanuric Acid levels at 30-50ppm. Think of CYA as sunscreen for your chlorine. Without it, the sun burns off your sanitizer before it can kill the algae.
2. Double Your Pump Run Time: In the winter, you might get away with 6-8 hours. In July, you should be running your pump 12-16 hours minimum, or even 24/7 if you have a variable speed pump on a low setting. Filtration is just as important as chemistry.
3. Brush the Walls: Algae likes to hide in the microscopic pores of your plaster. Even if the water looks clear, brushing once a week knocks those spores into the water where the chlorine can get them.

Austin Detail: The “Heat Dome” effect in Central Texas leads to massive evaporation. When you refill your pool with high-calcium tap water, you’re also introducing new minerals that can feed algae if your phosphate levels are high.

Don’t let the heat win. If your pool is starting to look hazy, give us a shout. We specialize in “Algae Interruption” for Austin backyards.

Sent from my iPhone while sweating through a service call in Leander.