Dumb question - does my liquid drop (4 bottle) test kit test free chlorine or total? The instructions don't really say but they imply free chlorine. They say if I wait 5 minutes after the initial 10 second reading then that is combined chlorine.
Testing for Free Chlorine
- Thread starter crokett
- Start date
The standard OTO test kit, which shows chlorine levels as different shades of yellow, tests for total chlorine. You can get a sense of how much FC you have if you are quick and are good at distinguishing the different yellows. For the first ten to twenty seconds after you add the drops it will show the free chlorine level and then it will drift over another twenty to thirty seconds to the total chlorine level. If you see an obvious color shift then you have combined chlorine. But I wouldn't count on being able to actually measure the free chlorine level, the color shift starts fairly quickly and is difficult to distinguish from the color change caused by mixing the drops into the sample and you have very little time to judge the shade.
Then I have the kit that only tests for total. The instructions do say if there is a color shift then you have combined. I don't see a color shift so either I don't have combined or I don't have any free. More than likely little to no free given the amount of algae that was in there.
