High Chlorine will Bleach Out DPD Test

In Tech Talk by Steve Donohoe3 Comments

It all worked out – goodies for all!

We left Las Vegas on Wednesday and drove down to Riverside into 100 degree temperatures (yikes! a record temp for Riverside in November!) for our CPO class this past Thursday and Friday, November 4-5.  The  drive took longer than we thought, so we couldn’t complete the set up until the first class day on Thursday morning.  Elise was running around like a crazy person trying to get everything ready while students were arriving (and that’s NOT the way she likes things to go), but it worked out.

This class was our largest so far in Riverside with 17 students! (which is why we had to retrieve our narrow classroom tables from San Diego, so there was room for everyone!).

The CPO students testing in Riverside.

We had an assortment of students:  old timers in the industry, newbies to the industry–in both commercial and residential areas.  Very good questions were asked, information shared, and positive feedback expressed about the excellent class curriculum and the benefits of becoming CPO certified for anyone associated with pools and spas. (We definitely concur on THAT point!)

The DPD Test can bleach out.


A CPO always knows the limitations of their test kit; for example:

♦ The DPD type colorimetric test to check free available chlorine will bleach out at high chlorine levels.

♦ Phenol Red will turn to a purple color at high chlorine levels.  This could be mistaken as a high pH when the actual pH is below 7.0

Steve and Kyle Maddox.

We also discussed the importance of taking care of your test kit, the shelf life of the reagents and the accuracy and limitations of all the other testing the Certified Pool Operator must perform.

Our thanks go to PoolCorp and to Riverside’s Manager, E. J. Wamsley and, especially, to Kyle Maddox, Riverside’s Operations Manager, who has come in on Saturdays to lock up after us (with last year’s classes), has carried down our classroom materials, and volunteered to standby for us as we tried to close down the classroom setting in a timely fashion at 5:00 p.m. each day  —  Thanks a bunch, Kyle!


  1. Hope all is well thanks again for the very intense class.
    So I can back to work yesterday morning at 6:30am to find my staff didn’t add any chorine tablets on to our system before leaving Friday afternoon, needless to say our pool was little cloudy, with our first patient to arrive for Therapy at 2pm giving me 7 1/2 hours to get this pool back in shape. Which included a backwash of the system
    Learning from what you trained us I was able to get my pool back in order by 11:30am. I took a water sample to my pool supplier because I was a little curios on what some of my true reading much to my surprise it all came back golden. This pool is used for Therapy 4 times a week with our water temp at 95% the size of the pool is 9×20 4.5 deep. It gets drained every 106 days but after your class this will be moved up to every 70 to 80 days what caught my eye was my TDS.

  2. I appreciate all the hard work and effort you and your wife put into the training, so thank you for the outstanding course.

    I’m new to the pool industry and I’m currently trying to start my own pool servicing business. If there’s any advise, assistance, or recommendations you could help me with I would greatly appreciate it. I’m excited about this new career and I just want to do the best I can.

    Thanks again Steve for the great course and all the useful information.

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