Here are abstracts from Volume 5 Number 1 of the Journal of the Swimming Pool and Spa Industry:

Benjamin D. Tanner and Charles P. Gerba, Ph.D.
Department of Microbiology and Immunology, and Department of Soil, Water, and Environmental Science – University of Arizona

Application of the Ct Concept for Determining the Disinfection of Microorganisms in Water

Recreational waters such as swimming pools and hot tubs are a potential source of microbial disease transmission among children and adults. In order to control disease transmission it is necessary to maintain an adequate level of chemical disinfectant. To accomplish this, the Ct concept can be used, where C is the disinfectant concentration and t the time required to inactivate a certain percentage of microorganisms in water. The multiplication of the two values produces a number which assesses the efficiency of a disinfectant. Ct allows for comparison of disinfectant effectiveness in general and with respect to different microbes or water conditions. The Ct concept, when applied to the disinfection of recreational waters, helps professionals in the field determine the amount of disinfectant needed to control pathogenic microorganisms in water and prevent the spread of disease.

John A. Wojtowicz

Chemcon

Effect of Cyanuric Acid on Swimming Pool Maintenance

Cyanuric acid is added to swimming pools to reduce photochemical decomposition of free available chlorine (av. Cl) by ultraviolet (UV) rays in sunlight. This is accomplished by formation of chloroisocyanyurates that do not appreciably absorb UV light. Recent data show that the av. Cl loss rate caused by sunlight is only about 1% per day at 138 ppm CA. This is consistent with the fact that over 99% of the av. Cl in CA stabilized pools is in the form of chloroisocyanurates. Virtually all of the decomposition (about 14% per day) observed in a bather-free pool in the summer time in the Phoenix area is due to thermal decomposition of chloroisocyanurates. Bather load can appreciably increase the av. Cl loss rate. Cyanuric acid, in combination with its ionized form (ie, cyanurate ion), also functions as a buffer to help stabilize pH.

John A. Wojtowicz

Chemcon

Sanitizer and Oxidizer Product Information Summaries

Summary sheets containing product description, properties, and performance data for various sanitizers, oxidizers, and sanitation systems shown below are based on the following published papers:

Wojtowicz, J. A., "Survey of Swimming Pool/Spa Sanitizers and Sanitation Systems", Journal of the Swimming Pool and Spa Industry 4(1)2001:9 -29.
Wojtowicz, J. A., "Use of Ozone in the Treatment of Swimming Pools and Spas", Journal of the Swimming Pool and Spa Industry 4(1)2001:41 - 53.

Some of the categories covered in the summaries include: disinfection, algae control, oxidation of contaminants, cost, and cost effectiveness.

1. Chlorine
2. Bromine
3. Ozone: Data on Disinfection and Oxidation
4. Ultraviolet (UV) Ozone
5. Corona Discharge (CD) Ozone (DIN Design)
6. Corona Discharge (CD) Ozone (Modified DIN Design)
7. Copper, Silver, and Zinc
8. Copper-Silver Ionizers
9. Copper-Silver Cartridges
10. Zinc-Silver Cartridges
11. Potassium Monopersulfate
12. Potassium Peroxydisulfate (Persulfate)
13. Polyhexamethylene Biguanide (PHMB)
14. Ultraviolet Light (UV) and Hydrogen Peroxide

John A. Wojtowicz

Chemcon

Swimming Pool and Spa Water Chemical Adjustments

This paper deals with adjustments to swimming pool and spa water chemical parameters such as pH, alkalinity, hardness, stabilizer, and chlorine. It discusses test kit acid and base demand tests and provides equations for calculating required acid and base additions for adjusting pH based on the test results. It also discusses a mathematical approach for calculating acid and base additions (and associated alkalinity changes) and pH changes resulting from addition of sodium bicarbonate (for alkalinity adjustment) and cyanuric acid (for stabilizer adjustment) based on swimming pool chemical equilibria. Tables, graphs, and a general equation are provided for determining required acid and base additions for adjusting pH. In addition, equations are provided for determining required chemical additions for adjusting alkalinity, hardness, stabilizer, and chlorine concentrations.

Kim Skinner

onBalance

The Total Dissolved Solids Contributions of Various Swimming Pool and Spa Balancing Compounds

The amount of total dissolved solids (TDS) contributed by certain swimming pool and spa balancing chemicals has been misreported in various publications of trade liturature. The correct contributions, as well as the calculations used to arrive at these figures, and the rationale which explains the errors, are dilineated.