In general, when pH points to acidic environment, the chances for corrosion increase and when pH points to alkaline environment, the chances for scale formation increase.
The pH values above 7 signify alkalinity, pH values less than 8.3, most of the alkalinity in the water is in the bicarbonate form, and scale formation is normally not a problem. However, when the pH rises above 8.3, the alkalinity converts from the bicarbonate to the carbonate and the scale will start to form. You want to keep the water alkaline, but not too alkaline. 10 or 11 is great for boilers where scale inhibitors are added to water treatment, but cooling water should be in the 8 - 8.5 range, not more than 9. Nalcool 2000 is particularly suited for small medium speed engines like the EMD (which, in my opinion is the best medium speed engine ever made, designed to be run and maintained!) and the recommended concentration of that chemical additive will maintain Ph in the required range.
You might want to keep an eye on other parameters, too, eg:
Total hardness, 170ppm Max
Chlorides, 40ppm Max
Sulphates, 100ppm Max
TDS 340 Max (Total Dissolved Solids)
Your Nalcool supplier should be able to provide a suitable test kit.
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