FishyReef
Broke Reefer!
I think adding salt directly to your sump would be pretty risky - hard to control salinity increases that way, and that stuff is pretty nasty if it hasn't had time to really sit for 24hrs. I personally would make up a slightly stronger batch of saltwater the next time you do a water change and slowly add the stronger batch, measuring your salinity as you go. You really don't want more than 0.001 change in salinity per day!