Remove old urine stone
The urine stone of our tenant has been there for about 10 years. Now we had the task to remove him. All acids, even formic acid and CO remained unsuccessful. At least the last big rest could not be gotten away.
The solution: First pretreat with acid, then heat with the Bunsen burner until the urine stone has turned brown and has begun to crack easily. Then push the toilet flush then I could easily replace the urine stone with a plastic spatula.
