Lights Out In San Diego

In Tech Talk by Steve DonohoeLeave a Comment

We had a little surprise occur during our CPO class this past Thursday and Friday, September 8-9, at PoolCorp’s SCP store! At 3:45 p.m. on Thursday, the lights went out — literally.  The whole power grid went down in all of San Diego County and parts of Mexico and southern Orange County.   When the power went down in our classroom, there was no more projector, no more Power Point presentation, AND no more air conditioning during a San Diego “heat wave!”  Well, we persevered and continued the class, anyway– “the old fashioned way” — with the CPO book and the instructor at the white board. Fortunately, the power came back on at about 2:30 a.m. on Friday, and we were able to finish up our CPO Certification class right on schedule.

The power outage experience did remind us of how reliant we all are on electricity and how its absence can so dramatically affect every aspect of daily life:  no street lights, no gasoline for automobiles, no microwave, no electric oven or refrigeration, and no restaurants serving meals….not to mention the thought of people being stuck in elevators in the dark, not knowing how long they would be there!….it does make one very thankful that the the outage lasted only a few hours and not 2 or 3 days!!

TECH TALK:  How do you test for chlorine in the swimming pool?

The First FAS-DPD reagent starts out Pink

The second FAS-DPD reagent ends in no color

Chapter 8 of the CPO Pool & Spa Operator Handbook’s is about “Chemical Testing,” and several chlorine testing methods are discussed in class:  DPD and FAS-DPD are two of them.   The DPD test is a colorimetric method, which simply means that two colors are compared.  In this case,  after the reagent is added, the water sample is compared to a color chart or block to determine the chlorine concentration.  The DPD kit tests for Free Available Chlorine (FAC) and Total Chlorine (TC).  If you subtract the FAC from the TC, you can derive the Combined Chlorine contaminants in the pool water.

The FAS-DPD test kit is a titrimetric method of testing.  This means that the first reagent added to the water sample will change it to a specific color (pink in this case).  Then when the second reagent is added, the sample will distinctively change to a different color (to “clear” in this case).  The second reagent  drop count  indicates the chlorine level.  Our Operator Handbook states on page 87: “Titration is more accurate for pool/spa water testing than comparator test blocks”.  The FAS-DPD also has a low resolution — about .2 ppm and can test chlorine up to 20 ppm — and it can directly test for the Combined Chlorine contaminants.


Again, we wish to thank David O. and crew at PoolCorp/SCP-San Diego for their hospitality — and we’ll see you guys again in October!

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