Cyanuric Acid also known as stabilizer is necessary in pool water. It blocks UV light from penetrating the pool and causing the chlorine to dissipate faster.
What many people don’t know is that it creeps up over a number of years. It comes in common shock as well as chlorine pucks/sticks etc. The only way to lower it is to dilute the pool. I recommend you backwash more frequently and for longer periods of time over the season as well as lowering the water more when closing. I would also recommend you shock your pool with a shock that doesn’t have cyanuric acid in it.
Cyanuric Acid is also helpful in keeping your liner soft and supply.
Normal levels are between 30-50ppm however often upon testing I see it 150 and up. This is where we need to develop a plan to lower it over time.
Have questions. Pop me a quick email and I would be happy to answer them.