On 2013-04-08, dadiOH wrote:

The roughness is from lime deposits which may be further stained by iron.

Definitely deposits. I got a lot removed with the Polident, but still
two heavy deposits. As a goof, I tried lightly scraping with a
screwdriver. Chunks of brown deposit broke free! I'll continue along
this line, but will try something that won't scratch the porcelain
glaze.

For the bottom of the bowl, shut off the water supply to it and flush so
that there is minimal water left;

I discovered a neat trick to help further empty the bowl. After
shutting off the water to tank and flushing, rapidly dump a gal jug of
water into the bowl, all at once if possible, and from several feet
above the bowl. Inertia of the falling jug water will remove even
more water, right down to jes above the water seal level, in my case.

Your long term solution is to soften the water. That will solve the lime
problem.....

CO water is notoriously soft. Our's is a little less soft than most
of the state, but still fairly soft water. I haven't bought bottled
water since I moved here. I think the deposits are calcium deposits
from human urine, the stain from the yellow in urine.

nb