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

amieelynne

Active member
Jun 5, 2007
33
Massachusetts
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??
 

waste

TFP Expert
LifeTime Supporter
Mar 29, 2007
4,160
Coastalish 'down easter'
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)
 

amieelynne

Active member
Jun 5, 2007
33
Massachusetts
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

waste said:
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)
 

mbar

LifeTime Supporter
Apr 24, 2007
257
Ashland PA
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 :shock: . 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 :-D