RO water should be pretty much free from dissolved solids.
So treat it like distilled water. If you want drinking water from your well water, RO is great.
Use RO water for evaporation make-up in the coolant recovery tank. Any closed system with a recovery tank loses some water to evaporation over time.
If you use RO water for make up with straight coolant, treat it like it is distilled water. Buffering products are usually economical to use with closed systems. A few ounces can be all you need.
Just remember, do it right,do it once. I have run cooling systems for 4 years without a need to drain & dispose of the coolant. As the glycol breaks down in to glycolic acid, the pH of the coolant shifts. Water that is free from magnesium salts & properly buffered extends the life of the coolant.
B.
