Not to step on Greg's toes, but do you have an Estes Chemical nearby? I know there are some in east Texas. They carry Trophymaker pond fertilizer which I have used with good success. It, however, is a quick dissolve fertilizer and is not designed to be used as you describe.
Otherwise try your local feed store and tell them the formulation you are looking for. They'll tell you if it is available.
BTW, you sould be able to buy Southern Excellence from one of this site's sponsors and have it shipped to you and see if it works for you.
