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Thread: strange new color results w/ HTH 5...help!

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    Join Date
    Jun 2007
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    strange new color results w/ HTH 5...help!

    I've been using the HTH 5 way test kit all season without a glitch so I figure why fix something that isn't broken...but I just went out and tested tonight only to see some really strange results! the chlorine side was yellow with the first couple of drops but by the 5th it had turned an ugly rusty red. the PH side seems to be reading 6.8, BUT it was 7.2 2 days ago and I added borax to raise it a bit because I also shocked the pool that day (day before yesterday)

    what the heck does a red chl result mean??
    27' round AGP, 2hp 2speed pump & 150sf cartridge filter --taking a stab at BBB and eyeing all the cool gadgets available for pools ;)

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    The ugly red usually means that you have LOTS of chlorine. Others could fully explain the reactions, but I know from experience that the 'brick-red' color means I have to either dilute the test water or use DPD-FAS to know what the true cl level is. The high cl may also be 'bleaching' the pH test (making it appear lower than it actually is). I'd trust that the pH is good, since you had 7.2 and added borax. You must have added a ton of bleach to shock to get this result - why did you add so much?

    In short, the 'red' result is because the cl is so high that it's changing the 'endpoint color' of your OTO reagent which means that you've got lots of cl in the water - try the 'shotglass' method to ~pin the cl level down. 8)
    Luv& Luk
    -Ted

    Having done construction and service for 4 pool companies in 4 states starting in 1988, what I know about pools could fill a couple of books - what I don't know could fill a couple of libraries :-D

    POOL SCHOOL, TF Testkits, Jason's Pool Calculator, CYA vs. cl chart, (Just a few DARNED handy links!)

  3. Back To Top    #3

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    I didn't add that much--1 gal of 12% in a 17,000g pool. that usually only brings it up to around 7-8ppm. I did it to shock it in preparation for closing and because after I pulled the stairs I noticed some algea in the area where they had been. I wanted to kill it off to make sure there were no nasties hanging around all winter. hmmm...so odd. I'm not familar with the shot glass method--guess I'm off to search again and try that. is there an easy way to lower chl levels? is it harmful to leave it high? thanks so much

    Quote Originally Posted by waste
    The ugly red usually means that you have LOTS of chlorine. Others could fully explain the reactions, but I know from experience that the 'brick-red' color means I have to either dilute the test water or use DPD-FAS to know what the true cl level is. The high cl may also be 'bleaching' the pH test (making it appear lower than it actually is). I'd trust that the pH is good, since you had 7.2 and added borax. You must have added a ton of bleach to shock to get this result - why did you add so much?

    In short, the 'red' result is because the cl is so high that it's changing the 'endpoint color' of your OTO reagent which means that you've got lots of cl in the water - try the 'shotglass' method to ~pin the cl level down. 8)
    27' round AGP, 2hp 2speed pump & 150sf cartridge filter --taking a stab at BBB and eyeing all the cool gadgets available for pools ;)

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    mbar's Avatar
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    I was using an old reagent for ph - it was fine at first, but then it started to behave really strange. The first test would look almost yellow - so much so that I did it again to see if I made a mistake by using the chlorine reagent instead of the ph one. Then after trying it again, and getting the same result, I thought my ph had mysteriously gon way down overnight. I decided to do the test again - it came out 7.3 . This happened a couple of times, and then I realized that it may be the reagent?? I bought some new reagent, and the problem disappeared.. Long story for saying check the reagent
    16x33 fiberglass pool sand filter

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