Yes, caustic soda does clean toilets and also removes limescale. However, you must be very careful when using it and make sure that it does not get on your skin. You must also make sure that you do not mix it with any other chemicals or cleaning agents.
1) wash it with prell shampoo. 2) wash it with dandruff shampoo that has tar in it. 3) wash it with shampoo mixed with baking soda. 4) Wash it with dawn wash detergent. 5) wash it with tide. Hope this helps :)