They work great! I bought the biggest one they have. I belive it is called a Mag Float. They come in two styles, 1 for glass & 1 for acrylic. I have read that the bigger ones work better because the magnets are bigger and more powerful but you have a large tank so you will want the largest size anyways. I have a very large algae eater and rairly use mine but it is handy. You never have to get your hands wet to clean the front glass. mine has been in my tank for 6 years and looks as good as new.