Brattens Clam Chowder

My mother in law made a recipe book of the recipes she uses the most.
On Sunday I made this Bratten's Clam Chowder---it was SO good (though probably not so good for you)!

2 cans minced clams (drained-reserve juice)
2 cups diced potatoes
1 cup diced celery
1 cup diced onion
3/4 cup butter
3/4 cup flour
1 quart half and half (add milk if too thick)
1 1/2 t salt (pepper to taste)
1/2 t sugar

Pour juice off clams over vegetables. Add enough water to cover and cook until potatoes are tender. (About 15-20 min).

In a separate pot melt butter, and flour and cook while stirring for 1 minute. Add half and half and cook until smooth. Add salt, pepper, and sugar. Add undrained vegetables and drained clams and warm thoroughly.