aly_starh
Fish Aficionado
i have now been using a toothbrush, buy the cheapest you can find. And scrub the glass, it works!
Get the worst of the deposits off with a razor. Then use some vinegar to attack the deposit and soften it followed by a non-scratching Scotch-brite. I completely wore out a Scotch-brite cleaning a new used 55 but it did the trick.
The acetic acid in vinegar is easily removed from an empty tank by rinsing it out after cleaning. It is not for a tank with fish in it.