fhorta: You can't really mix and match our advice with others advice if they aren't the same. If you have the K-2006, you simply run the FAS-DPD test using the R-0870 powder and R-0871 drops. You can measure up to 100ppm with it.

If you aren't keeping your FC at shock level (20ppm) as BigDave advises, YOU WILL NOT KILL THE ALGAE!