I am using the PS234 kit. I did as you suggested and filled tube with pool water to the 25ml mark instead of 10 ml. But I need more detail. I put in only 1 scoop of the powder, do I need to add more than 1 scoop? I added 46 drops of FAS-DPD #2 until sample turned clear. How do I calculate the FC? I added 5 drops of FAS-DPD #3 and sample stayed clear.