Drain Defense Pipe Build-up Remover 64-fl oz Drain Cleaner

I have been using this product for a number of years and have been very pleased. When we first started using it, the drains ran a little faster and then clogged all of a sudden. I called the plumber who recommended this product and told him what happened. I was told that it's very possible that a large chunk broke free and is blocking the drain. The plumber told me to use it for another three days and see what happens. On the second day one of my children used the shower and the water drained pretty quickly. I continued to use it until there was no backup. After that, I used it twice a month and my drains are working like new. But you need to be patient. You'll be glad you waited.

works surprisingly well. haven't had a drain problem since I started using it