I poured salt in and then plugged the unit up the next day. However, I found out the electrician didn't properly place the small sensor on the motor so my salt generator wasn't working for two weeks. To make long story short, we properly plugged up the generator board, found this incredible website (after spending about $70 at the pool store for 'shock' packs) then started with the bleach and muriatic acid to get my chemistry correct. Once I got it clear with bleach, the swg started generating the chlorine from the salt I put in 3 weeks prior.
However, I think you are supposed to start the swg immediately to start generating chlorine. You will eventually have algae if you don't do it. If you are confused or don't know how to turn it on, I would start putting liquid bleach in the pool so you will have some chlorine until he gets that thing hooked up. Keep in mind my experience consists of exactly 3 months since I built my pool this year.
Hope this helps.
Bookmarks