First off, you wasted your time sealing the grout, although the river rock could be sealed. Epoxy grout can't be sealed, but I don't think that's what's happening here. It almost sounds like your shower pan is holding water, and it's causing a pink mold to form. The reason I say that is that it's also now beginning to affect the very bottom of the wall joints. It's tough to say for sure without physically inspecting it, but that would be my guess. Either the shower pan wasn't presloped, or the weep holes at the base of the drain have blocked up, or both.

We have that issue as well. I know it isn't the pre-slope because the white shower curtain turns as well. It's our water.

It must be the water because it's in the kids shower as well and yes, on the curtain! What is that? Sue36, have you done anything about it?

I doubt that it's the water, although water with high concentrations of iron can lead to rust coloured stains (which bathroom cleaner won't remove). More likely, it's mold -- and it grows just as easily on shower curtains as it does on tile. The root of the problem is moisture or dampness, compounded by warm conditions and lack of air circulation. If the tile (and underlying bed) or the curtain aren't drying thoroughly and quickly after the shower is used, pink mold is very likely to form -- and will thrive.

The only solution is to figure out why things aren't drying completely, and fixing the cause.

The floor is river rock so the water doesn't drain as well as other tiled floors but it's not like it doesn't dry. I would not characterize the bathroom as warm and damp. We live in the NE and it's pretty cold. Also, I was told that the grout itself has a protectant against mold. I'm not sure what can be done if the floor is draining and drying.

A peachy-colored tinge can be a sort of mildew. Even though you sealed the stone, you have epoxy grout, and decent drainage, the shower can still retain enough humidity to allow it so bloom.

I'd first make sure the vent is properly sized and is moving the amount of air that it's supposed to. Too many turns in the duct, or loud air noises from turbulence can indicate that the flow is restricted more than it should be.

I forget, did you put the fan on a timer so that it runs after the shower is turned off? We've had a few of those theads, I don;t recall if you were one that was doing that. If not, consider it. A delayed timer switch like those sold at EFI will run you $30-$50.

Mongo

While it may look as though your shower floor is dry, if the underlayment and pan are holding water because the pan or membrane weren't properly sloped toward the drain when the shower was built, or if the weep holes in the bottom of the drain are clogged, water or moisture will be retained in the underlayment (which is a porous masonery product) beneath your river rock. When that happens, even though the floor of the shower may appear to be dry, moisture or damp remains below the visible surface, and mold becomes a problem.

Bill Vincent or Mongo can probably tell you if there's some way to unclog weep holes without tearing out the shower floor (I'm not an expert - I went through a similar problem in a house I once owned), but if the pan or membrane weren't properly sloped, the only solution is to tear out the shower floor, and reinstall it properly.

And alas, unless you're taking only cold showers, the tile in your shower is subject to warming up during a hot shower -- even though you're in the northeast.

We have this problem in our front load washer, in the gasket of the supposedly air tight (or water tight) door. When I posted on the laundry forum, someone said that it's a kind of bacterium. I noticed it, too, in our toilets when we came back from a two-week vacation. Anytime our water stands for a while, we seem to get it. Not sure if that's what you have but I thought I'd share.

We have the same problem in our new (two-month old) shower. It has a natural stone floor, with near-white spectralock grout. Despite regular cleaning, the grout is staining pink in several places, especially around the drain (It was built on the Schluter System). I have noticed that the water pools around the drain and in the other places where the floor appears lower than the drain. Should I be raising heck with my contractor, or is it expecting too much to have the shower floor sloped toward the drain, and installed so that the drain is the lowest part of the floor?

Thanks!