Review on Enhance Your Aquarium's Filtration with Fluval Biomax Filter Media by Alicia Jones

They work very well but they are a lot larger than they appear in the picture. In my 80 gallon filter I only had to put about 4 filters. I have used some from another company and they were much smaller and could hold more. I don't think I'll get efficiency from them just because I can't fit enough in my filter. I would suggest only using them for larger applications. I bought two boxes but I think it will last a lifetime lol.