I'm not sure about the toilet cleaner, wouldn't that possibly be too corrosive?
You don't leave them in there for a long time , or over night. soak for a few minutes , scrub with a plastic brush and rinse in water. For the stuff you get to use at home might take a little more effort?
But the white vinegar mentioned after I posted sounds like a good alternative , it's not sure acidic , I'll have to give it a try .
