Oto turns orangish colored when testing. What?


Well-known member
May 13, 2009
So I know my chlorine level was 18 on 5/12, then dropped to 13.5 on 5/13 (night time, removed solar cover), and was only .5 lower on 5/14 (morning). I assumed today it was still high...but for giggles, I used my oto test when checking ph (7.5), and the test sample turned momentarily orange with each drop. I've had high chlorine before, but it was just a dark yellow. Could the iron in my water be affecting my tests?

My water is clear from the top but not across. (when the light is on at night it is milky and I can see all different sizes of stuff whiz zing by)

I've had to add tap water so I know there is iron in the water. A trip to the pool store is in order for tomorrow to get the metal out stuff...gosh I hate paying for that stuff but what do I do?

My reagents are less than 1 year old. My other numbers are from 5/10:
TA 160
Ch 320
Cya 40.

I'm sure the TA and ch are up thanks to 1000 gallons of tap water. Cya will also be down which would account for the quick drop in fc the other day.


Eta:clarification on overnight loss.