It did look like salt deposit to me as well. Its why i asked about foliar spraying.
I do think its just your tap water also.
But if you want a good pest preventative. Yeah. Spray some neem.
If its outside, and still in veg. Id personally spray for sure.
Follow the directions on the product label to a T.
Dont spray in the middle of the day either.
Spray at dawn, or dusk.
Avoid using it at all, during bloom.