How do I accessible a closed coupled cistern. I looked-for to enjoy a look inside but cannot bring the lid bad.? Wanted to add some parazone anti-limescale point into the cistern itself -...

Wanted to add some parazone anti-limescale point into the cistern itself - cannot figure it out....back. The flushing mechanism is on the top of the cistern and so I cannot lift up off the lid
What type of steam source could I bring...
Answers:    if it is a two flush cistern the two push buttons erect out and there is a screw lower than them if it is a one flush it could unscrew to let the lid raise off
How I do I drain the pressure on...
Is the flushing machinery on the top of the cistern round - if so you can unscrew it and get the lid bad that way!