How do you get rid of stains?

Use moriatic acid to eliminate those stain. Be sure to use gloves and a tile brush with long handle. In order to avoid skin irritation or problem. Use mask as well. Bleach and cleanser has no able to eliminate those stubborn stain. Those products are used usually to maintainance for day to day use.

Soak the place with toilet cleaner for 10-15 minutes then brush it until it clears. There are strong acids too used to whiten the toilet's floor but its dangerous to our health if prolong exposure.

I think what you are experiencing is "hard water" mineral stains, beings that they are white or brackish! Being a tiler by trade, hard water will also discolor the grout! There are several products on the Market, like "CLR" and "Lime Away" that will assist in dimiminshing these stains by following their directions implicitly. I CAUTION you, seriously....Use MURIATIC ACID with great respect. It is very, very toxic to your lungs. DO NOT even open the bottle, without having really good ventilation in the room..all windows open...a good fan blowing. DO NOT get any on your skin....it is, as it says...ACID. I would use it only as a last resort. Good luck..and it is best to use the less toxic cleaners often..a large build-up is hard to remove!