Built for Pipes. Not Pools
Langelier Saturation Index (LSI)
For decades, the swimming pool industry has relied on the Langelier Saturation Index (LSI) to measure water balance. But there is a fundamental problem: Dr. Wilfred Langelier invented the LSI in the 1930s for closed municipal water pipes, not open bodies of water like your swimming pool.
While the LSI focuses heavily on pH to predict scaling in dark closed pipes, it fails to account for the unique, open-air environment of a swimming pool. This reliance on outdated "range chemistry" often leads to a constant battle—adding acid to lower pH, then adding bicarbonate to raise alkalinity, endlessly "bouncing" your water chemistry and wasting money.
The Missing Piece
The Hamilton Index (HI)
Developed by United Chemical founder Jock Hamilton, the Hamilton Index was built from the ground up specifically for swimming pools. It recognizes a scientific truth that the LSI misses: in an open system, Total Alkalinity is the key to preventing stains and scale, not just pH.
How It Works The Hamilton Index simplifies water care by comparing your Total Hardness to Total Alkalinity. Instead of forcing you into a narrow, unstable pH range, it determines a safe "Alkalinity Ceiling" specific to your water's hardness.
- No more pH bounce: By allowing a naturally higher, more stable pH (7.8 – 8.2), you reduce the need for constant acid adjustments.
- True Balance: We prioritize the relationship between Hardness and Alkalinity to lock in water clarity.
Superior balancing
The Hamilton Advantage
Prevent Stains
The LSI was designed for pipes where staining wasn't visible. The Hamilton Index specifically prevents the precipitation of minerals that cause unsightly pool stains.
Less Chemical
By working with your water’s natural tendency to rise in pH, rather than fighting it, you use significantly less acid and buffer.
More Reliable
This isn't theoretical; it is the practical, proven method that has been proven effective time and again in the real world.
Easy Balancing
Have a pool that is safe, sparkling, and simple to maintain.
GET STARTED
Balance with the Hamilton Index
Choose how you want to use the index
Use the Calculator
Input your test results and get instant feedback on your balancing.
Download the PDF
Download the Hamilton Index PDF chart and use it to start balancing.
