Armando,
I have found it much more 'fun' to clean the glass when using a magnetic cleaner as my arm is dry and I can look in the tank at the same time. Most of the magnetic cleaners will not effectivly clean coraline algae, and have a tendency to scratch the glass, but I have a work around.
I purchased one of the really large Tunze mag. cleaners, and use that on the outside, while using a small magnetic scraper on the inside that had razor blades in it. The small magnetic scraper is too weak to use on thick glass, but when using the Tunze on the outside it makes up for that weakness. The scraper is pretty small, and it therefore takes some time, but I don't mind if I can look into the tank. The Tunze magnets are quite expensive, but the small inside scraper is only about $7 or so. The blades are pretty decent, and do not rust as fast as razor blades, particularly if you rinse the salt off each time. You can purchase replacement blades direct from the manufacturer (Penn Plax I believe) for very low $. If you are over some time I can show you how this works.