We have a 4 year old Raritan Atlantis head that has stains in the bottom that look like dirty water stains. We've tried cleaning with CP and nylon scrub pads and still can't remove the stain. What should we try next. By the way we have an Owens Kleen Tank MSD Type II.

If C.P. on a scrubber wouldn't touch 'em, they're hard water mineral
stains. Some Comet or Softcrub on a sponge or plastic scrubber should
remove 'em. If not, try some LimeAway or CLR--also only on a
sponge or scrubber or just enough of it sprayed onto the porclain to
coat them if you need to wait a bit for it work. Make sure to
"mop" up any cleaners before flushing...the small amount needed to use
a sponge or scrubber isn't enough to upset the balance in your tank,
but isn't good for the toilet "innards."

You can also try "ZUD" heavy-duty cleanser. It works miracles with rust stains, etc., in a toilet bowl. You can get it in the Janitorial section of Home Depot, etc. Real cheap, and a can of it'll last you a couple of years if you keep it dry. If you keep it's use down to monthly or less often, it won't hurt the glazing in the toilet bowl - just don't go crazy with it and use it every day! I wouldn't use it for pots and pans, but for a toilet it's just fine.

Thanks to both of you. I'll try it today and let you know the results.

Tried ZUD and it worked great. Very easy, no scrubbing. Thanks