I recently bought a 70 gallon tank that was used for saltwater fish in the past, and i cant seem to remove the water stains from the inside. I mean I've tried everything I can think of, from soaking the stain in vinegar, scraping with a razor blade, even tried glass cleaner and the classified section from the paper. None of these seem to work, and I would really love to get the stains off before setting up the tank. Please help!!