Skip to content
TheBlueprintof Water

Enter the water you tested. Read the tendency at the pipe wall.

Operating Case

Enter your system parameters. Results update automatically.

Measured pH of the water you are evaluating (tower water, not makeup, if you are evaluating a tower).
pH

Measured, on the water you are evaluating. 5 to 11.

Use the hottest surface the water touches (condenser or exchanger skin) for a conservative check; bulk temperature for the sump.
°F
Saturation pH (pHs) at 90 °F7.34 LSI +0.66
From your test kit. If you only have total hardness, calcium is typically 60 to 75% of it.
ppm
Methyl orange, or total, alkalinity.
ppm

M alkalinity, ppm as CaCO₃.

Total dissolved solids, a primary LSI input. Estimate from conductivity if needed.
ppm
If you enter makeup water and cycles, calcium, alkalinity, and TDS are multiplied by cycles; pH is not. Enter the tower's measured pH, or use the Scaling Potential Calculator to predict it.
×

Leave at 1 to evaluate the water as entered. Cycles multiply calcium, alkalinity, and TDS; pH is never multiplied. Enter the tower’s measured pH, or predict it in the Scaling Potential Calculator.

Click on any stream to learn more.

Saturation at the Pipe Wall

All quantities are live and update with your inputs.

Operating Conditions
pH
8.00
Temperature
90 °F
Calcium
200 ppm
Alkalinity
150 ppm
TDS
500 ppm
Cycles
1×

Key Results

Primary outputs and operational context based on your inputs.

Where the three disagree, your water is probably poorly buffered. See the note on PSI.

Langelier Saturation Index Langelier (1936) with the Larson and Buswell (1942) approximation for pHs. Positive leans scale, negative leans corrosive.

+0.66 LSI

Scale likely

pHs 7.34

Ryznar Stability Index Ryznar (1944). Weights the saturation pH twice; the bands run inverted, under 6.2 leans scale and over 6.8 leans corrosive.

6.68 RSI

Balanced

pHs 7.34

Puckorius Scaling Index Puckorius and Brooke (1990). Ryznar's bands on an equilibrium pH computed from alkalinity, the only estimated pH on this page.

6.96 PSI

Corrosive

pHeq 7.73 from alkalinity. Reads against Langelier here.

Saturation pH The pH at which this exact water would rest in equilibrium with calcium carbonate at this temperature.

7.34 pHs

A 0.17 · B 1.95 · C 1.90 · D 2.18

Hotter, harder, more alkaline water saturates sooner.

Cycled Water The water the indices are evaluated on: the entered analysis times the cycles.

500 ppm TDS

Ca 200 · Alk 150 ppm as CaCO₃

At 1 cycle, the water as entered.

Scaling Potential Calculator

Want cycles, a temperature sweep, five minerals, predicted tower pH, and acid feed? The pro room runs the full carbonate model on this same water.

Open the Scaling Potential Calculator

Save this to a site, free account

A free account holds saved systems and named comparisons. The calculator itself never needs one.

Inputs are serialized to this device before anything navigates. Abandon sign-up and the page restores them for 30 days. No password, ever: the link signs you in.