I've started putting this in all my tanks . I can see the difference . The most noticable thing is that the SLUDGE buildup is greatly reduced . For example , I used to have to remove my slate and clean it by hand .. with Bio-Care Waste Control , I no longer have to do that - it stays clean . Keep it in the fridge , and buy it in small quantities , as onve once opened up , the bottle seems to be less effective .