Reading Salifert Ca test..
 

When I test Ca using my Salifert kit, instructions say to keep adding drops until the stuff turns from purple to clear blue. Problem is, it doesn't just flash from purple to blue in one drop, but it slowly turns a little more blue with every drop, and when it does seem to turn blue, it goes back to purple within a minute. At what point am I supposed to stop the test?

Thanks.

Mason, it should turn to clear blue over a range of 2 or three drops. Once the color stays blue for more than a few seconds, you can consider it having reached the end point.

Thanks Brad. I'll use that as the end point. This may mean that my Ca levels have been lower than I thought. Whoops...