I have a Salifert test kit and have tested for calcium as the first stage in the test kiytbut when I reach step 8 adding x2 level spoons of Sr-5 I get a light ink/purple colour. Then 12 min later I need to add drops of Sr-3 until the colour changes to blue. Problem is after 12 min the colour is already blue! Does than mean my Strontium level is off the chart low and I ned to add this element or is my test kit faulty. Or possibly too old as I have had it for a long time...