Hi. We have moved to a semi rural older house (requiring restoration). We have replaced the septic tank with a modern management system, and put in shiny new loos- one of which is beginning to stain, as I can't use loo blocks or toilet cleaner containing bleach. Obviously I have been cleaning with soap and a loo brush. I have also put sterident tablets down each loo regularly as I think this is safe. The loo that is staining is an inexpensive tiny one - the only one we could find to fit a very tight space, (and comply with building regs) - so likely of poorer quality. The water level in the pan drops slightly between use, so a ring is beginning to form, just above the water level.
What can I use to keep the loos looking nice (which won't damage the environment or septic system)? Which products and perhaps brushes do others use?
Thanks