The Impact of Cyanuric Acid on Pool and Spa Water, ORP, and Amperometric Controller Probes

The Impact of Cyanuric Acid on Pool and Spa Water, ORP, and Amperometric Controller Probes Thomas M. Lachocki, Ph.D. Director of Product Development BioLab, Inc.

The Impact of Cyanuric Acid on Pool and Spa Water What is cyanuric acid and how does it get in the Water? General acceptance & drivers for use. Sanitation studies Impact on ORP Probes and Controllers

Cyanuric Acid (CyA) ( Stabilizer ) Structure O H N O HO H N O H HO N O H H N O N H Cy A H N N OH H o r N N O H Cy A

Dichlor Structure & Hydrolysis Reaction Sodium dichloro-s-triazinetrione Dichloroisocyanuric acid dihydrate O H N O Na + 2 H 2 O Cl N O N Cl CyA + HOCl + NaOCl

Trichlor Structure & Hydrolysis Reaction Trichloro-s-triazinetrione Trichloroisocyanuric acid Stabilized chlorine O Cl N Cl N O N O Cl 3H 2 O CyA + 3 HOCl

Cyanuric Acid and Chlorinated Isocyanurate Chemical & Physical Properties CyA Trichlor Dichlor Physical form Granules Granules & Granules Tablets Water solubility Moderate Slow Fast Chlorine Content 0% 90% 56-62% CyA Content 98% 55% 50-59% NFPA Oxidizer NA 1 1-3

Trichloro Remaining in Skimmer (7oz, 3" puck) % Remaining 100 90 80 70 60 50 40 30 20 10 0 0 1 2 3 Days (10hr.)

Chlorinated Isocyanurate Use Volumes Used in U.S. Swimming Pools (82-97) 1.5 billion lbs 40 trailers @ 44 M lbs 258 miles Washington D.C. to New York, or Dallas to Houston, or Los Angeles to Las Vegas (almost) 3 pucks, 13.5 wide 3,000 miles New York to Los Angeles Johnson, L.J., Chemical Economics Handbook, Chlorinated Isocyanurates, 1994

Form of Chlorine Used by Service Professionals (1,350) to Treat Pools & Spas by Region Region Trichlor Bleach Cal Hypo Dichlor Gas N.East 84 52 39 52 <1 S.East 95 10 70 35 <1 Florida 74 84 33 16 7 M.West 79 50 57 50 7 N. Cal 80 78 15 41 2 S.West 82 39 44 35 5 N.West 100 50 50 75 <1 S.Cal 83 93 6 46 2 D.Dickman, Service Industry News, July 2000.

Cyanuric Acid Toxicology CyA is safe for swimmers. No evidence of fetotoxicity, teratogenesis, effects on reproductive performance, mutagenesis, or carcinogenesis. Hammond, B. G., et al. (1986). Env. Health Pers. 59, 287-292 (Consurtium)

Cyanuric Acid Toxicology Not toxic to rats at 10,000 mg/kg rat > 1.9 lbs CyA/170 lb CyA is eliminated in excreta w/ rats, dogs, and man ( 14 C Studies) 170 lb 64 oz water 200 mg/l CyA 4.9 mg/kg No Effect Level for Male Rats 154 to 371 mg/kg

% % Chlo rine Re maining vs. Time (hrs ) @ Vario us CyA Le ve ls 100 80 60 40 20 0 0 4 8 12 16 20 24 28 Ho urs FACi = 3ppm; 84 F; ph = 7; * Extra pola te d Levels 0 ppm 20 ppm 100 ppm 200 ppm*

Impact on Sanitation Properties of Chlorine

Inactivation of Streptococcus faecalis and Staphylococcus aureus [CyA], mg/l 99% Staph. Inactivation, 99% Strep. Inactivation, 0 0.5 min 0.3 min 25 11 min 7.2 min 50 15 min 11.5 min 100 25 min 21.7 min Dichlor; ph=7.0 purified water; 0.25 mg/l FAC 1965 paper :...caution should be used if [this study is] extended to actual swimming pool operations. Anderson, J.R. (1965) Swim Pool Dtat & Ref Annual 32, 121. Anderson J.R. Ph.D. Dissert. U. WI Civil Eng.

Purified Water Studies That Support Slower Disinfection With CyA Longer chlorine contact times were required to kill E.Coli (gram negative)and S.faecalis (gram positive). 1 Higher chlorine concentrations were required to kill 99.999% of E.Coli, S.faecalis, S.aureus. 2 1. Stuart & Ortenzio (64). Soap Chem. Spec. 40(8), 79-82, 112-113. (USDOA) 2. Robinton, & Mood (67). Am J. Public Health 57, 301-310. (Smith & Yale)

Purified Water Studies That Support Slower Disinfection With CyA The 99.99% Inactivation rates for P.aeruginosa, S. aureus and S.faecalis are slower at high CyA levels (0-360 mg CyA/L tested). 3 Analysis of equilibria constants were performed to explain the slower disinfection observed in distilled water systems. No consideration of pool water was included. 4 3. Golaszewski & Seau (1994). Wat. Res. 28(1), 207-217 (Lab Res Env. Et Sante, France). 4. Wojotowicz (97). JSPSI 2(1), 34-41; ibid 2(2), 14-22 (Olin).

Impact of CyA on E.coli (18M/ml; ph=7.4; Lab Water) Chlorine, mg/l [CyA], mg/l Organisms in 20 min, x 1,000 NaOCl 0.55 0 8.7 0.56 0 10.0 K-Dichlor 0.56 0 2.2 0.56 100 1.5 0.57 100 0.7 K-Dichlor 0.80 0 1.9 0.86 0 0 0.81 100 0 0.84 100 0 Ditzel, R.G. et al (1961). Swim Pool Age 35, 10-14 (Monsanto)

Escheria coli and Staphylococcus aureus Disinfection Cyanuric acid did not interfere with chlorine s ability to kill the test organisms. ph = 7.2 ; Swimming pool water not used. [Chlorine] = 0-1.0 mg/l [CyA] = 0-100 mg/l Researchers compensated for chlorine demand due to microbiological culture medium. Time to completely destroy the test organism was measured. Gilcrease & Morgan (63). Swim Pool Age 37, 30-38 (U. Florida)

Inactivation of Streptococcus faecalis a [CyA], mg/l NH 3 - N, mg/l 99% Inactivation, (minutes) 0 - < 0.25 25-4 50-5 100-12 0 0.05 20 b a. Sodium hypochlorite; ph=7.4 demand-free water; (0.5 mg/l FAC). b. 99.9 % Kill time with demand free-water or Madison Tap Water (corresponds to 0.18 ppm NH 2 Cl). Fitzgerald & DerVartanian (67) Appl Micro 15(3), 504-509 (U of WI)

Inactivation of Streptococcus faecalis a [CyA], mg/l Water Type NH 3 - N, mg/l c 99% Inactivation, (minutes) 0 b 0.1 100 100 b 0.1 50 0 b 0.2 135 100 b 0.2 85 0 pool 0.3 150 100 pool 0.3 90 a. Sodium hypochlorite (0.5 mg/l); ph=7.6-7.9 b. Distilled-demand-free and Madison tap water yielded similar results. c. NH 4 Cl and diluted secondary sewage effected kill time similarly. Fitzgerald & DerVartanian (67). Appl Micro 15 (3) 504-509 (U. of WI)

Pool Water and Distilled Water are Not the Same Killing times are always comparatively long in a real swimming pool situation [compared to distilled water] whether cyanuric acid is present or not. The reason is presumably the effect of ammonia and amines. Gardiner, J. (73). Water Res 7, 823-833 (U.K. Dept. Env.

The Impact of CyA on Chlorine Disinfection to E.Coli, P.aeuruginosa, S.aureus & S.faecalis. Study Phase 1: Distilled water Four organisms [Chlorine] = [CyA] = Contact Times = 10 6 Organisms 0.6 to 2.2 mg/l 0 to 200 ppm 0 to 20 min Swatek, Raj, Kalbus (1/21/67). NSPI Conv (Cal State).

The Impact of CyA on Chlorine Disinfection to E.Coli, P.aeuruginosa, S.aureus & S.faecalis. Study Phase 2: Commercial Pools in Lakewood, CA Indoor & Outdoor Pools Swatek, Raj, Kalbus (1/21/67). NSPI Conv (Cal State).

Conclusions: It was verified that cyanuric acid seemed to delay the bactericidal effect of chlorine in distilled water. This finding confirms previous studies (Anderson, Stuart, et al.) It was shown that in actual swimming pool waters this negative effect was not generally seen. In some instances cyanuric acid accelerated the chlorine disinfection (in pools). S. aureus & P.aeruginosa were the most resistant < 10 min to kill 99% @ 2.2 mg/l FAC & 0-200 mg/l CyA Swatek, Raj, Kalbus (1/21/67). NSPI Conv (Cal State).

Impact on Algicidal Properties of Chlorine

Influence of Cyanuric Acid on Chlorine as an Algicide CyA Concentration = 0, 25, 50, 100, 200 ppm. Cl 2 Concentration = 0, 1.0, 1.5, 2.0 ppm Algae Strains: Phormidium Minnesotense (Black), Pleurchloris pyrenoidosa (Mustard), & Oocystis sp. (Green) Water and algae strains were chlorine demand free Only Mustard Algae survived 2.0 ppm chlorine regardless of the CyA level Chlorine toxicity to pool algae is reduced slightly. Increasing the concentration of CyA (from 25 to 200 mg/l) did not result in an additional reduction in algicideal efficiency of chlorine. Sommerfeld, M.R. & Adamson, R.P. (1982). Appl., Environ. Micro. 43(2), 479-499.

Conclusions: It was verified that cyanuric acid seemed to delay the bactericidal effect of chlorine in distilled water. This finding confirms previous studies (Anderson, Stuart, et al.) It was shown that in actual swimming pool waters this negative effect was not generally seen. In some instances cyanuric acid accelerated the chlorine disinfection (in pools). S. aureus & P.aeruginosa were the most resistant < 10 min to kill 99% @ 2.2 mg/l FAC & 0-200 mg/l CyA Swatek, Raj, Kalbus (1/21/67). NSPI Conv (Cal State).

Purpose: Public Pool Disinfection Assessment, Pinellas County, FL 1. Guide public pool management 2. Understand CyA s impact on disinfection. Rakestraw, et al. (94). NSPI Int. Expo. 11/11/94; Vattimo (97). NSPI Chem. Symp. Proc. 89-93.

Public Pool Disinfection Assessment, Pinellas County, FL Study Structure: 1. 486 Commercial Pools; July - Nov. 1992 2. Unannounced - County Public Health Unit 3. Analyses by Pinellas County Water System # of Bacteria Water Chem. Sanitizers Environmental Characteristics Pool Characteristics Algae Rakestraw, et al. (94). NSPI Int. Expo. 11/11/94; Vattimo (97). NSPI Chem. Symp. Proc. 89-93.

Pinellas Study Bacteria Tests: Heterotrophic Bacteria < 501 CFU/ml Total Coliform Bacteria = 0 CFU/ml Non-Coliform Bacteria = < 201 CFU/ml Rakestraw, et al. (94). NSPI Int. Expo. 11/11/94; Vattimo (97). NSPI Chem. Symp. Proc. 89-93.

Sanitizer Breakdown: Pinellas Study Sanitizer Used # of Pools Trichlor 282 Sodium Hypo 113 Cal Hypo 77 Chlorine gas 7 Bromine 6 Rakestraw, et al. (94). NSPI Int. Expo. 11/11/94; Vattimo (97). NSPI Chem. Symp. Proc. 89-93.

Cyanuric Acid Levels: Pinellas Study [CyA], mg/l # of Pools 0-10 109 11-20 21 21-100 234 101-200 98 201-400 22 401-800 2 Rakestraw, et al. (94). NSPI Int. Expo. 11/11/94; Vattimo (97). NSPI Chem. Symp. Proc. 89-93.

Chlorine mg/l % Pools that Passed Bacterial Tests Micro Tests Total Pools [CyA] = 21-100 mg/l [CyA] = 101-200 mg/l 1-5 Pass 290 145 60 1-5 Fail 42 13 7 % Passed 87 % 92 % 89% Rakestraw, et al. (94). NSPI Int. Expo. 11/11/94; Vattimo (97). NSPI Chem. Symp. Proc. 89-93.

Correlation between Cyanuric Acid and Bacteria in Commercial Pools Variable Cyanuric Acid Correlation Value Prob > R # Exp. Fecal Coliform No 486 Free Chlorine Yes 0.11 1.20% 486 Heterotrophic Yes -0.09 3.76% 486 Bact Total Coliform No 486 Non-Coliform No 486 P. aeruginosa No 27 S.aureus No 27 S.faecailis No 26 Rakestraw, et al. (94). NSPI Int. Expo. 11/11/94; Vattimo (97). NSPI Chem. Symp. Proc. 89-93.

ORP (in mv) Effect of CYA on ORP Probes Before and After Cleaning 800 750 Brand X Brand Y 700 Brand Z 650 Before Cleaning 600 0 30 60 90 120 150 CYA (in ppm) - Balanced pool water, 5 ppm CYA added each hour, ph = 7.5, chlorine = 4.5ppm - Before cleaning, lower and erroneous readings (+/- 50mV) were observed.

ORP (in mv) Effect of CYA on ORP Probes Before and After Cleaning 800 After Cleaning 750 Brand X Brand Y 700 650 600 Before Cleaning 0 30 60 90 120 150 CYA (in ppm) Brand Z Brand X Brand Y Brand Z - Balanced pool water, 5 ppm CYA added each hour, ph = 7.5, chlorine = 4.5ppm - After cleaning, higher and more consistent readings (+/- 15mV) were observed.

ORP (in mv) Amperometric (Cl2 in ppm) Amp. and ORP Probes Response to Chlorine Addition 800 6 750 700 650 5 4 3 600 550 Brand X ORP Amperometric 2 1 500 0 1 2 3 4 5 6 Time (hr.) - Balanced water, 0.5 ppm chlorine added each 0.5 hr, CYA = 200ppm - Amperometric probe response is much faster and more linear. 0

General Conclusions: Maintaining ph & Chlorine is Important for a Sanitary Pool. ORP is not a Suitable Measure of Sanitation CyA Levels up to 200 ppm Do Not Inhibit Disinfection. Cyanuric Acid Chlorine Lock