Free tool
Pool LSI Calculator (Langelier Saturation Index)
The LSI tells you whether your water is corrosive, balanced, or scaling. Corrosive water eats plaster and heaters. Scaling water clogs plumbing and salt cells. Enter your readings and get the number with a plain-language read.
Never mix pool chemicals. Add one chemical at a time, always to water, never water to chemical. Let the pump circulate between additions. Acid and chlorine must never be combined, they make toxic gas. Add acid to the deep end and let it circulate.
Step 2: Current readings
Enter what you have. The calculator uses whatever you give it.
Enter pH, total alkalinity, and calcium hardness to get your LSI water balance number.
Your dosing amounts show up here as you enter readings.
This is a guide based on standard industry dosing. Water chemistry varies. Verify with your own test kit, add chemicals in smaller steps, and retest before adding more. You are responsible for what goes in the pool.
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