It s not a sign that your toilet is not clean.
Calcium deposits in toilet tank.
You can use distilled white vinegar or a chemical product such as lime away or clr.
Cause of calcium deposits calcium deposits in toilets are caused by hard water which is water that is high in mineral content such as calcium and magnesium.
You may notice that if your bathtub has a dripping faucet you will eventually see calcium stains in the tub.
Lactic acid acetic acid gluconic acid formic acid hydrochloric acid boric acid.
The truth is that the calcium deposits that cause these stains will pop up wherever there is water flow.
Fill a spray bottle with distilled white vinegar.
You may want to wear gloves and use eye protection if you are using a chemical product.
Spray the calcification liberally.
When hard water passes through the plumbing system the calcium in it will get caught in small nooks and crannies causing a build up that can restrict the size of a sewage pipe.
Flush the toilet to lower the water level and expose the calcification.
How to remove calcification from toilets.
Turn off the water supply to the toilet.