Shock level, based on your CYA level, and the Best Guess chart.

Until that 1 ppm combined chlorine residual is gone, you'd expect to encounter smells and odors.

Also, I hadn't picked up on the fact that you had a cover you could take on and off -- you need to leave it off. Chlorine + solar UV is MUCH more effective against organic residuals than chlorine alone. If you are traveling again, and can't keep an eye on it, then cover it. But if you are there, leave it uncovered, both so the sun can irradiate it, and so the volatile organics can escape.