I am going by Ben's "best guess chart". While the cya would protect 3.5 ppms of chlorine, it is not enough to kill all of the algae. The shock level for a cya of 35 would be 15ppms. My understanding of this chart is taking it up to 5 would not be enough to kill all the algae. It would keep it under control for a while, but not kill it all at one time will cause you trouble any time your chlorine is low. I know that when I start to have problems holding onto chlorine, I don't always have cc, or the smell of chlorine right away. I have found it easier to deal with it at the first sign by taking my chlorine up to shock and leaving it there until the chlorine holds overnight. In my opinion you are right on the border of controling the algae bloom. You have enough chlorine in the water to keep killing algae, just not enough to kill all of it.When I was battling my swamp in the beginning of the season, I didn't smell anything in my pool, but the chlorine was still being used up overnignt. It did use less and less as time went by, but it did take a while. I am only giving you my suggestions based on what I have experienced. It is up to you to do what you think is best.