Water Chemistry

The toughest part of managing any aquatic facility is often finding that magic formula where your pool, spa or spray ground water is clean, clear, eye-burn/odor free AND easy on your hardware, filters and pool surfaces.

It’s a lot to ask of anybody. To help you out, we talked with Clayton Womble, Plant Maintenance Supervisor, University of North Carolina in Chapel Hill, NC and his maintenance staff. Here’s what they had to say:

1. How many pools do you operate?

-One indoor competition pool. 50 meters with two movable bulkheads, 8 lanes.

2. What is the size of your pool (in gallons)?

-949,000 gallons.

3. Free available chlorine residual - How do you measure for free chlorine?

-We use a colorimetric test kit, Taylor K-2005c

4. The minimum recommended ppm for free chlorine is .4 pmm. What level do you keep your pool(s) at?

-1.5 ppm

5. Total Chlorine Residual -- There is debate on where this measurement should be (anywhere from .3 to .5 ppm above Free Chlorine), where do you keep yours?


6. Since pH is so important in determining the life of your filters, pumps, etc. What pH do you keep your pools at? Why?

-7.5 because the human eye is about 7.5 pH

7. How do you measure total alkalinity & calcium hardness? Where do you try to keep alkalinity (in ppm's)? Where do you try to keep you calcium counts (in ppm’s)?

-Colorimetric test kit

-Alkalinity 110ppm

-Hardness 510ppm

8. What temperature do you keep your pool(s) at?

-81 degrees

9. What equipment do you use to automate the water chemistry process?

-Strantol MG/L5 controller with ultraviolet disinfections system.