Bleach may open your drain line, but it will also dehydrate the remaining grease in the drain line making it as hard as concrete. As mentioned in earlier posts, if it does not open your line it can make it dangerous to use chemical based drain cleaners. i would use a bacteria that is earth friendly, such as Grease Away available from Mr. Rooter, It has the best strain of vegetative bacteria that eats the grease that causes 80% of blockages in kitchen drain lines. it may take a couple of applications, but it is earth friendly and is very safe to use. The only bi-products are carbon dioxide and water.