Our shower goes pink very quickly around the drain area and the plumber said it was caused by hair conditioner (the same in the slot of the washing machine where the fabric conditioner goes, that needs taking out and scrubbing quite often).
I hate to tell you what our plumber said but it is actually fat/grease being washed off the body and it turns pink around the drain area. I've used Vical on ours and got rid of it but you have to keep it clean to stop it coming back.
Lakeland sell a mildew spray which cleans silicone sealant - I notice in my shower that often the silicone goes pinky before black spots appear and I use the spray then.
I'm staying at my daughter's bungalow, where she has a wet room with a shower cubicle. It has grainy type flooring, which is awful in the shower cubicle part Any suggestions as to what might fetch it up a bit cleaner? Its discoloured to an almost red hue I've tried white vinegar, without much success I presume its residue from shampoo, etc? (that, and not being cleaned often!)