ccp2,
To directly answer your question, it is very unlikely that adding a couple of bags of salt, when the cell is on, is going to damage the cell..
Just to be clear.. Salt has nothing to do with 'shock' There is no such thing as "salt shock"..
There is zero reasons to add chlorine 'shock' to a saltwater pool.
If you can see green algae, then running a SWCG will never get the pool back to being clear... The algae will consume more chlorine than your cell can produce.
We'd be glad to get you pointed in the right direction... Just let us know if you are interested...
Thanks,
Jim R.