Cook the bacon in large dutch oven or soup pot over medium high heat until it has turned brown and crispy. Once the bacon has browned remove it to a paper towel lined plate. Discard all but 1 tablespoon of the rendered fat.

Add leeks and celery to pot and cook them until they begin to soften (about 5 minutes), stir frequently.

Reduce the heat to medium and add the potatoes and clam juice, add thyme now if including. Simmer the vegetables until the potatoes can be easily pierced by a fork, about 15 minutes. Meanwhile, crumble or dice the bacon strips into small bits. Reserve about 1 tablespoon of the bits for garnish.

When the potatoes are tender - reduce the heat to medium low and add all of the milk, then return bacon (minus 1 tablespoon) to the pot and add the fish.

Simmer the chowder on low to medium low heat, make sure it does not begin to boil. The chowder is ready when fish has cooked through, about 15 minutes. The fish should be flaky but firm.

Toss in a handful or two of finely chopped parsley and add additional salt and pepper if desired. Keep the chowder on low heat until ready to serve. Garnish with additional parsley and reserved bacon.