Drain the canned clams and set aside, saving the juice. Add the liquid drained from the clams and the bottled clam juice to a medium saucepan. Heat to a boil and add the chopped onion and diced potatoes. Cook over medium heat until the potatoes are for tender and the liquid has reduced. Skim off and discard any foam the develops on top. Add the half and half and remove from heat. Cook the diced bacon in a small skillet until crispy. Remove the bacon and keep the bacon grease. Add the butter to the bacon grease and heat until the butter melts. Add the flour a bit at a time whisking constantly. Cook for one minute but do not allow the roux to brown. You want a light roux for this soup. Add the half and half to the soup pot and heat to a simmer. Add the roux to the soup and cook until thick. Add the chopped clams and bacon. Cook until the clams are heated through. Add salt and pepper to taste. Serve hot with chopped chives and chowder crackers on top.