Can I repair a crack in a fish tank or do I have to buy whole new one?
It is normally best not to repair cracks in fish tanks unless you are highly skilled and using techniques similar to that of windshield repair technicians using similar quality equipment. The strength of a repair will never be that of the original glass/plastic and it is normally best to remove the entire side of the tank that was damaged and replace it with a new sheet of glass or acrylic.