Ive seen post out there about the warnings of overdosing but I dosed under the recommended dosage and has now killed 3 fish in my tank. Be very careful with this product. I have a 32 gallon tank and have dosed 3 times in 3 weeks. First two weeks I dosed one cap the first week and 2 the second week and saw my firefish die. I checked my params and the only thing I noticed is my ammonia went down from .15 to 0. I went to my LFS and told them what happened and they said no way it could have been the waste away and continue dosing, I dosed half of what was recommended again this week which is 2 caps of this product and now have 3 dead fish with my 4th that is on his way out. Im sure it depleted the oxygen in my tank as all my fish were hanging out at the top of tank the past two days. I know I should have listened to myself and stop dosing after the firefish died. Im writing this to warn people about this product and that not only overdosing can cause problems but even adding 1/3 or 1/2 of the recommended does can also do harm . I know alot of people have had success with it but I would recommend you consider some product other than waste away. Since I have only had this tank for a little over a year, this is my first big mistake and what a costly one it was. 2 clownfish and a goby have survived with my blenny not doing well at all. My take away from this product is that it might not be made for smaller tanks. All this tragedy for trying to get rid of gunk under my sandbed. Be careful with this product.