Hi, Bobby,
You're almost right. Test your Cl again before adding more and only add enough to bring your Cl back up to 15.
(i.e.) If you test and Cl is 5, add 10 to bring it up to 15.
I assume your reference to CYA is off the recommended level from Ben's "best guess" table.
The speed with which your water clears will be influenced quite a bit by how frequently you test and add Cl. CAPTCHEMICAL posted some interesting info......he tested 6-8 times daily and cleared his pool in three days only......pretty good!
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