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**First, take a deep breath!** This is a chemical imbalance, not a catastrophe. CYA (cyanuric acid) is a stabilizer that protects chlorine from UV degradation, but at 200+ ppm, it's severely inhibiting chlorine's sanitizing power. The science is clear: high CYA creates chlorine lock, allowing pathogens to thrive despite normal chlorine levels. For a gunite pool in California, you need immediate action: **partial draining and refilling** is the only effective way to lower CYA. Test your tap water first - if it has high CYA too, you'll need to use reverse osmosis treatment or truck in water. Don't add more stabilizer products!

Nancy's right about the science, but let's talk **health implications**! High CYA means your chlorine isn't working properly, which creates a breeding ground for bacteria, viruses, and algae. Swimming in that water could lead to skin infections, ear infections, or worse. I'd recommend **stopping all swimming immediately** until you get this under control. Also, check what products you've been using - many chlorine tablets and shock treatments contain stabilizer, so you've likely been adding CYA without realizing it. Switch to unstabilized chlorine (like liquid bleach) once you get levels down.

As a parent, this terrifies me! Our kids swim daily. **Please don't use chemical drain cleaners or harsh treatments** - that runoff is awful for the environment. Partial draining is necessary, but do it responsibly: drain slowly to prevent erosion, and if possible, direct the water to landscaping that can handle chlorinated water (not vegetable gardens!). Once refilled, consider more natural maintenance: ozone systems or UV sanitizers can reduce chlorine dependency. And going forward, test weekly with a good test kit - prevention is everything! My family uses a simple Taylor test kit every Sunday.

Good points from both! To clarify the **draining calculation**: you'll need to replace about 50-75% of your water to get CYA below 100 ppm (ideal is 30-50 ppm). Calculate your pool volume first. Since you're in California, be mindful of water restrictions - check local regulations. Also, test your calcium hardness and total alkalinity before draining, as fresh water will change these. Rebalance everything after refilling. **Pro tip**: Use the Pool Math app or a similar calculator to determine exact amounts.

Adding to the health angle: **test for combined chloramines** too! When chlorine isn't working properly due to high CYA, it can create chloramines that cause respiratory issues and red eyes. After you drain and refill, shock the pool with unstabilized chlorine to break down any remaining contaminants. And please, **wear gloves and eye protection** when handling chemicals - safety first! Once balanced, your water should be crystal clear and safe. Consider installing a saltwater system for more consistent sanitation without stabilizer buildup.

**Long-term prevention strategy**: We switched to a mineral system with a small amount of chlorine and it's been wonderful - no more stabilizer issues! Also, use a pool cover when not swimming to reduce chlorine loss from sunlight (that's why people overuse stabilizer). Teach everyone who maintains the pool about CYA - most people don't understand it until there's a problem. And remember: clear water isn't necessarily safe water! Test, test, test. Your local pool store might offer free water testing, but invest in your own reliable kit for regular checks.