potassium testing

Has anyone tried to use Hach (product nr 2459100) reagents for testing Potassium in a Hanna Checker with a 610nm led eg. the one for Alkalinity to test the Potassium level in a reef tank? If so did it work or not? If it worked could you please share the absorptionformula and the Hanna checker...

Well, I finally decided to join the crowd especially since I want to grow out some nice sps pieces. After doing some reading on potassium I decided to pick up a test kit. I found Amazon had a Salifert available, so a day later it was in my mailbox. Having ran out of my Reef crystals last...