Tips for using a Taylor DPD pool chemistry kit

Tips for using Taylor N, N-diethyl-p-phenylenediamine (DPD) pool chemistry test kit

The information on this page will give you some helpful tips to improve the accuracy, precision, and reliability of your pool water chemistry testing.

1. If the free chlorine is above 10 ppm, the following may happen:
   • It bleaches out test chemicals
   • It flashes pink when test chemical drops are added, then clears, indicating high chlorine
   • High chlorine can interfere with the pH results
   • High chlorine can interfere with alkalinity
   • If free chlorine is high, dilution is the solution. Testing water with high chlorine often yields inaccurate results. The water can be diluted and the results multiplied by a factor to calculate the actual free chlorine. Use a 25% dilution or 1:3 dilution ratio and multiply the results by 4 to obtain the free chlorine.
2. If the DPD solution is cloudy- after adding Ferrous Ammonium Sulfate (FAS)-DPD powder or DPD#3, this could indicate the following:
   • High hardness (above 500 ppm)
   • High Total Dissolved Solids (TDS)
3. Rinse before refilling your test equipment as traces of chemicals can interfere with results.
4. Use rinsed caps, not fingers, to mix solution.
   • Traces of chemicals on unrinsed caps or your fingers can interfere with results.
5. Throw test chemicals on deck or grass, not in pool.
6. Hold reagent bottles vertically (up and down) when adding drops.
   • There can be as much as 50% difference in the droplet size if held at an angle.
7. If chlorine test powder (FAS-DPD) is black, get new chemicals.
   • Moisture changes the white chemical’s color. (Can last indefinitely if dry.)
8. Testing reagents have shelf lives. Always check the expiration date of your testing reagent and replace when they are expired.
9. Never use your palm or hand to cap the sample cell. Always use the cap provided.
10. Match colors in natural light or use a special lamp that simulates daylight for testing indoors. Incandescent and fluorescent lighting (and sunglasses) alter color perception.
11. After a test, flush out the sample cell with fresh sample water several times to avoid having residual contaminate the next test.
12. To prevent contaminating reagents, always replace bottle caps securely right after using, and don’t exchange bottle caps.
13. Don't interchange one manufacturer's reagents with another's because they will not be equivalent strength.
14. To keep reagents fresh, store them out of direct sunlight, away from treatment chemicals, and out of extreme heat or cold.

Compromised reagents

The following are signs of compromised/damaged reagents:

• Unusual colors
• Black FAS-DPD
• Staining of the containers
• Liquid reagents exceed their use-by date, or over a year old if no date.
• Reagents won’t dissolve when shaken
• Floating particles
• Crusty dropper tips