We just remodeled the bathroom. I installed a glass block wall on one side of the shower (runs above the bath faucet/handle and below the shower faucet, separating the tub/shower from the vanity). I used the manufacturer's installation system of plastic spacers and silicone instead of mortar and filled in the joints with a white non-sanded grout. I then added a layer of clear acrylic latex caulk with silicone in it. A short time later, maybe 2-3 weeks, some of the grout lines started to turn a bright greenish yellow. What is causing this, and how do I fix?

My house is a 4-bedroom, 2-bath cape cod. There is a full dormer upstairs, with 2 good-size bedrooms and a full 5' x 8' bath with shower over an olive green (yes, really) tub. This bathroom needs remodeling because there is some water damage behind the tile and the shower head was mounted too low on the wall. Downstairs is a smaller full bath, 5' x 7', also with a shower over tub. The tub has high walls, a very curved floor, and is chipped in a number of places. This bath also needs a complete remodeling. The house was built in the 1950's; the downstairs bath is original. The dormer was added in the late 60's, the upstairs bath is also original. I want to replace the tub in the downstairs bath with a shower pan when we remodeling, just in case we have to "age in place" (we are in our 50's). But I am reading in some places that having only one tub means your house is no longer a 2 full bath house with "just" a shower. The issue seems to be young families raising children. Since neither of these bathrooms is big enough to have a tub and separate shower, and I am not about to knock down walls to enlarge them, am I compelled by resale issues to replace a tub that may cause problems if we have to age in place? Is it OK to have only one tub and a shower? Is there something that's a hybrid; perhaps a low-sided tub that's shorter than a conventional tub but higher than a shower pan?