I would consider what using acid on metal pipes would do. Mine are copper and cast iron. Id never dump muriatic acid down my drains. I dropped some metal in muriatic acid once just to see what happens. It was impressive.

wreckdiver has it right.

Acid is the go to cleaner for a lot of landlords between tenants on crusty toilets and works extremely well. I used it dozens of times during my plumbing days. It will effortlessly dissolve the crud in the holes and jets where it is impossible to manually clean. Soak and occasionally dip from the bowl and pour back down the flapper hole.
It is harmless to CHINA fixtures, like most toilets, but never use it on enamaled fixtures like enameled steel sinks or tubs. It will destroy the finish. The acid strength reduces fairly quickly with water flush or dilution. A 50 /50 mix with water will work, and is mostly neutralized by the scale it is removing unless you have grossly overdosed it. (Think vinegar and baking soda reaction, self neutralizing, sort of)

However, due to potential safety issues I don't recommend it's use by amateurs inside their occupied home. If you do... rubber gloves and eye pro... open windows FIRST, before you start.

quote:

Originally posted by bigeinkcmo:
Not sure if it would work but I use bar keeper’s friend to clean up a variety of surfaces. Might be worth checking out and it’s super cheap at places like Target.

^^^This, but don't buy from Target.... Lol

Swimming pool industry has an acid substitute. It is much more friendly than muriatic.

Go to Walmart, buy 2 or 3 gallons of white vinegar, turn off water & empty toilet bowl, pour in vinegar & let it sit for a few hours, presto all clean!

I use a wet/dry 600 grit. Clean the bowl, squirt in some more cleaner, don some gloves (if you are a wussy. I have had my hands in more shitters then I can count) and gently scrub the ring. You can feel the buildup. The first few minutes you will not think you are doing anything but soon enough the ring will start to disappear. Keep scrubbing and the ring will be gone. You can feel when you hit the actual bowl. Depending on how bad your water is this can a an annual or bi-annual thing. And it never damages the bowl.

USMC field days. It still works lol.

I should add that a great way to keep your toilet clean is a product called Flush & Sparkle made by Fluidmaster, available on Amazon.

I connects to your fill tube and to the overflow. It has easy to change chlorine cartridges, but only treats the bowl, therefore saving damage to tank parts. I have not had to clean our toilets since I started using them.