Algae - need a primer!

[heymom1]

Son just told me that CYA level is 100. I"m going to do the test myself to see what is going on. Now, bear in mind we have just added 1.5 lbs. of Zappit. (I know, but hubby wanted to do something right away, and I didn't have enough confidence in the strictly bleach method until I get the info. from you guys.)

Thanks.

Also: What does "Vacuum to waste" mean? We have no vacuum mechanism, only a Polaris. I can run the Polaris with a fine mesh bag, but I don't know if that will actually clean out the algae.