Vani-Sol Professional Toilet Bowl Cleaner (32 fl. oz., 3 pk.) by VANI-SOL If you're ready to replace your toilet because the stains and smell are absolutely VILE, then give Vani-Sol a try. Vani-Sol Acid Toilet Bowl Cleaner is a complete toilet bowl cleaning deodorizing and odor eliminator solution because the liquid formula neutralizes rust and old stains that other cleaners leave behind because of their much weaker formula. Vani Sol is not like those ineffective tablet, gel or drop ins systems that still leave you with a skid-marked toilet and that faint leftover smell of feces mixed with a fresh scent. Make sure the bathroom is properly ventilated, use gloves and wipe up any accidental spills quickly. Just twist the top, then give it a continuous swish up under/around the toilet bowl. You'll hear it bubble and start to work immediately. I like to wait 10 or 15 minutes then use the toilet brush to slough off the gunk that's been liquefied and watch it come off like heavily steamed wallpaper. Yes; It's grossly satisfying. Powerful liquid dissolves even the toughest stains including built-up lime deposits, hard water scale and rust stains! Even though it's used in industrial applications, it will NOT harm septic systems.