Combine cucumber and onion slices in a large bowl, layering with salt; cover with cold water and ice cubes. Let stand 1 1/2 hours. Drain; rinse; drain again. Combine remaining ingredients in a large saucepot; bring to a boil. Add drained cucumbers and onions and return to a boil. Pack hot pickles and liquid into hot jars, leaving 1/4-inch headspace. Add 1/8 teaspoon Pickle Crisp to each jar for added crispness. BWB 10 minutes, pints. 20 minutes for quarts.