While I'm no chemisty major, I'd say the drastic increase in alkalinity (by adding the baking soda) caused the calcium to precipitate out of your salt water. Basically... you had a calcium snow storm, and that's what all the white is. Either that, or all the baking soda didn't dissolve, and it's baking soda that you're seeing on your rocks. Either way, I'd say if you don't have salt water mixed up already, start mixing and storing. Do some major 20% water changes every other day or so for a week. That should help bring your water parameters back in shape. Agree with cccapt... with that much baking soda at once, your alkalinity and pH shouldn't be "normal", as your snails are letting you know.
Keep an eye on your ph/alkalinity/calcium levels and give this a read...
... it'll probably help you out in the next several weeks as you try to get your water parameters back in shape. "Live and learn" is so true... many of have been there already!