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What is the difference between the Langelier, Ryznar, and Hamilton indexes?
Keith B. Janus
Janus Mechanical Consulting

It is simpler and it works...

Bill Tech II

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Bill Tech II

tastes great, less filling.

ummm thats not very helpful, I know langilier is calcium, tds, pH, temp, and alk., rizer is supposed to be a Corrosion Measurement?
Keith B. Janus
Janus Mechanical Consulting

I believe that they are all equations based on the TA, temp, CH, pH. I believe they are just different scales based on different philosophies.


Most of the pool industry uses the langlier index, and it has been relatively successful. I personally feel they are like diets. No carb, no sugar, no fat, all fat, some fat, all carb, all sugar..... People get on their soapboxes touting whichever they prefer to be the best at the time.

I use the langlier index and create rule of thumb pool care based off of that, because if my clients had to sit down and calculate equations, they would be more likely to fill their pools in.

Well I have used the Langelier since I started with pools. I just recently heard of the Hamilton and the Ryzner. I was just curious as to the nature of these, I found a little blip on the Ryzner that wasn't very helpful, but nothing on the Hamilton. One more question for you. When you give your index calculation, do you take TDS into account, the reason I ask is I have a slide calculator that just says saturation index. It takes in account for temp, pH, calcium, and alkalinity, but no TDS. Since the TDS reading changes the end result so little, I was wondering if this was probably still a langelier(calcium) index.
thanks for your help guys.
Keith B. Janus
Janus Mechanical Consulting

I dont believe that TDS is really relevant so the SI index otherwise in a salt pool you would seriously have to compensate the TA PH and CH for all of the solids from the salt.

Thank u for help sir.
Keith B. Janus
Janus Mechanical Consulting

Oh Bob Lowry, we miss you !

I just started reading his chlorine book, guy knows his stuff!
Keith B. Janus
Janus Mechanical Consulting

On 2/11/2006 1:15:42 PM, Rob Treibel wrote:
>I dont believe that TDS is
>really relevant so the SI
>index otherwise in a salt pool
>you would seriously have to
>compensate the TA PH and CH
>for all of the solids from the
>salt.
>
>
>
Saltwater is aggressive. Use higher values for the TDS factor for salt pools. If you use the traditional index values of 12.1 for TDS less than 1000, 12.2 for 1000-2000, 12.3 for 2000-3000, etc., use 12.4 or 12.5 for pools with salt chlorine generators. When the Gulf of Mexico overran a pool in a recent hurricane and the owner allowed the water to remain in the pool for several months, the Gulf water, though plenty hard and high in pH, had 33,000 ppm salt, and the plaster became so degraded you could scratch it off with your fingernail.

It wasnt the water that caused it.

There is a local pool that pulls water right out of the puget sound in the seattle area. This pool has a white plaster finish, and its plaster is holding up fine.

Both the Langelier and Ryznar indicies are used to predict scaling (but  are not considered useful to predict aggesivness or corrosiveness to plaster by many experts) .  The  Ryznar Stablility  index is based on empirical evidence from obervations of scale thickness and water chemistry in municipal water systems. It is supposed to  have some usefulness in predicting corrosiveness to steel The Langelier Saturation Index is a theoretical model of calcium carbonate satuation and pH is the main variable in this equations with temperature being the second most important. By this it means that biggest changes in the index will come from a change in pH or temperature. This goes along with what we commonly observe, high pH tends to create scaling conditions and low pH tends to create corrosive conditions.

The Hamilton Index was developed by Jock Hamilton of United Chemical based on empirical observation of swimming pools and usually is used with 'high pH' pools.  Most pools on this system run at a pH of around 8.0.  It is also interesting that many of the bromine based products that are made by United chemical function better at a higher pH.  

Waterbear:::  I thought that Jock Hamilton preferred to keep the pH at 7.8.  I could be wrong.

Ken 

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Ken B

Hamlton index balance is achieved by adjusting pH to between 7.8 to 8.2, testing total (not calcium) hardness, and then adusting TA according to the Hamilton Index chart.  Since the recommened pH range is 7.8  to 8.2 I stand by what I said about the pH being around 8.0!  Just google Hamilton index and you will find one of the charts that was designed by United chemical with this info on it!