Takes longer than 5 days if your clog is bad

My kitchen sink was clogged and I had tried Draino but it did nothing. I saw good reviews for this product and decided to give it a try. I was skeptical at first because it said to repeat the steps for 4-5 days, but the water actually started to back up even more by that time. I persisted to use that along with a baking soda/vinegar/hot water (not at the same time as BioClean) and I am happy to report that after maybe what was 2 weeks, it finally worked.