Water (rust) stains on Caulk? Help!

what if you were to put a rag soaked in Iron Out on the caulk and then cover it with plastic wrap and let it sit over night. The idea is to get Iron Out in contact with the caulk for a long enough time to penetrate the caulk. Never tried this with iron out but it works well with mildew and bleach,

caulk around our tub, turning it orange. I'm getting tired of re-caulking this every year! Anyone have ideas???

I use oxalic acid (wood bleach) mixed in hot water, to remove orange iron stains from fiberglass shower stalls. Spray it on, wait a minute, and spray it off. Wear rubber gloves, as I've heard oxalic acid can get absorbed in the skin, and cause bad things.