On 2017-05-25, Martin Brown wrote:

On 24/05/2017 20:18, wrote:
I'm new to Septic tanks and have recently moved to a house in a hard
water area that has 5 toilets, all of which are badly stained. I presume
I can't use brick acid, Harpic toilet "pills", or similar so how do I
de-scale the loo? With a wooden scraper?

You can use brick acid - just get it approximately neutral again by
adding sodium carbonate or bicarbonate before flushing it away.

What you mustn't do is use chlorine bleach - that will kill the bugs. If
all else fails drop a dead hen in the septic tank to restart it.

"voodoo plumbing"