jonathan18: @Rikkitic: I was wondering whether you had a successful outcome to this problem?
We’ve got a similar buildup on one of our toilets (no idea why - the other toilets are fine, and we’re on standard reticulated water), and before I go pick up some LCR to see if that sorts it I thought I’d check on how you managed to sort it.
We rented our house out for a year, and when we got back into it, the toilet had some pretty severe (and dirty) calcification, scraping wouldn't work to remove it.
We were about to replace the toilet, but thought we'd give Vinegar and Baking Soda a go - poured most of a bottle of White vinegar in, and a tablespoon of baking soda. It foamed up as expected, we left it for half an hour, came back and flushed the loo - most of it was gone and the rest came off easily with a scrub.
I would skip the baking soda, it would just neutralise the vinegar.
Yep, I did wonder about that at the time, but did use both; it did something to the calcification (even with scrubbing), but not a huge amount - perhaps partly as it's years of build-up, but also perhaps the addition of the baking soda took the sting out.
I bought a big-as bottle of vinegar the other day, so will try again with only that (and similarly will remove most of the water to ensure it's a higher concentration).
Good to read above that LCR didn't do anything, so I'm saved from wasting money on that as a solution!