Pool Chemical Calculator & LSI

Pool chemical calculator for the numbers from your own water test: PoolChem works out the LSI water balance and how much liquid chlorine, cal-hypo, dichlor, trichlor, baking soda, calcium chloride or stabilizer to add to reach the target you set, for your pool volume.

ENTER YOUR NUMBERS
FC (the chlorine reading from your test), pH, total alkalinity, calcium hardness, CYA, water temperature and optional TDS. FC, pH, TA, CH and CYA each show a general typical range as a reference and highlight values outside it; those values are still calculated. A field left empty, or a number the app cannot use, is marked and left out of every calculation.

WATER BALANCE (LSI)
PoolChem calculates the Langelier Saturation Index from your pH, temperature, calcium hardness, CYA-corrected alkalinity and TDS, and tells you whether the result reads as corrosive, balanced or scaling.

HOW MUCH TO ADD
• FC with liquid chlorine 12.5%, cal-hypo 67%, dichlor 56% or trichlor 90%
• Total alkalinity with baking soda
• Calcium hardness with 77% calcium chloride
• CYA with stabilizer
The current value comes over from your test; you set the target. The result is shown for your pool volume together with the basis it uses, for example 12.5 g of available chlorine per 100 mL for liquid chlorine. Lowering values and pH adjustment are not calculated.

VOLUME AND UNITS
Work out the volume of a rectangular, round or oval pool in feet or metres, or type a figure you already know. Use US units or metric throughout.

TEST LOG
Save each test with its time, compare FC, pH, TA, CH, CYA and LSI across tests, follow the LSI line for your last 20 tests and delete entries you no longer need.

GOOD TO KNOW
The app works only with the numbers you type in. Strength varies by brand and age of the product, so follow the label, add in portions, let the water circulate and test again.

This app is not a medical device and does not diagnose, treat, cure or prevent any medical condition. Consult a healthcare professional for medical advice, diagnosis or treatment.

Recent changes:
PoolChem gets a new icon: a white drop half-filled with deep-blue water, beside a pipette letting fall a coral drop. Your saved water tests and settings remain the same.