Help with testing water

[Wizaugh]

Here's our results
FC 2
CC 2.5
TC 4.5
pH 8.2
CH 250
CYA, here's where I'm having trouble. I've got the tf100 and i guess I'm not understanding the test completely. We've done it twice and still don't understand the whole "black dot" thing. Can anyone explain it to a layman?

 

[Butterfly]

Try the Extended Test Kit Directions. Also, the article contains a link to Taylor Technologies that has a pic or two of the process. Post back if you have q's.

extended-test-kit-directions-t25081.html

 

[Wizaugh]

Thanks. Guess we did it right, we just have 0 CYA.