no1 rule never poor salt into the tank. lol
put it in a bucket(buckets FTW)
and leave it for a day/night to settle down test the saltinaty wth a salt messure aka hydromeater.
if it's in the correct lines safe for marine animals poor it into the tank but i use a filter in my buckets only little ones to keep the movement running around to make sure no salt sits at the bottom power heads would be just as good.
right now i have 4 buckets running at this time with 4 filters (filters cost me £5 each lol.
aslong as water is moving the salt stirs and dissolves properly.
there might be other methods butthis works for me at this point in time.
hope this helped