What Would Cause DPD No.1 Water Test To Turn Yellow?
by Chris
The results are always pink when adding the tablets. When I topped off my pool with chlorine and did the test, the colour was yellow. I did notice this batch was DPD No. 3 tablets. Would this be the cause? Thanks for the question Chris The DPD No.1 tablet is used to measure free or "available" chlorine. DPD No.3 tablet is used after the DPD No.1 to measure total chlorine or bromine. The difference between the two is the combined chlorine (chloramine) or bromine. If I'm reading the question correctly it might be that you may have skipped No.1 and went directly to the No.3 tablet. This may have caused a wrong reading. Or by some chance the factory may have put the wrong tablet in the packet. It does happen from time to time. When readings look strange, always double check and do another reading. This time really look at what you're doing. If you get the same results, then you know something is wrong. Another reason could be that the chlorine may not have had a chance to fully circulate throughout the system. Sometimes you may hit a "hot spot" of chlorine right after you add it. I always tell people to wait until the water fully circulates through the system (normally about 10 - 12 hours) after adding chemicals to test the water. For the most accurate readings I would encourage you to look at a Taylor FAS-DPD K-2006 test kit. It has everything you need and the one most pool professional use. Water Testing Kit Pool Water Testing The Pooltester and LaMotte Testing Tablets are the main ones that use the DPD tablets. Hope this helps and have a great swimming season Robert Comment By Chris: Thanks Robert for the help. It's made it alot clearer for me to understand. I think I need to use No.1 as I've never had any problems with these. I will let you know the results. Once again many thanks. Chris Comment: Wrong Tablets DPD no.3 tablets are for measuring total chlorine levels, and are supposed to be added to the tester after DPD no.1 tablets have already been used to determine free chlorine levels. You then have a sample containing a DPD1 and a DPD3 tablet, with the ensuing result showing you total chlorine levels. The problem is simply that you are using the wrong tablets. Get some DPD no.1 tablets. If you then want to know total chlorine levels, add a DPD no.3 tablet. Google total chlorine, combined chlorine and free chlorine. |
