Again, I'm not a builder and there are some initial things we here about and our professional members confirm that seem counter-intuitive. This may be one of them: running for 48 hours w/o chems. Plus, if he warranties his work, you want to follow his directions so he can't claim you violated the warranty and therefore he's not responsible.

A solar cover hold in heat and can also reduce chlorine loss particularly due to evaporation. If you get a high end solar cover and do everything right you'll get a full 3 to 4 years out of it. If you buy a cheaper one and aren't as careful, it will only last 3 seasons and maybe a little bit more..... Been there, done that. Go ahead and add chlorine as you need it.