What do I use to clean the calcium out of a plastic portable potty in my house?
Lemon juice and vinegar and excellent to get rid of calcium buildup in a toilet. I like this because the toilet you have is plastic and it won't damage the plastic toilet. Your second option is to buy a plumber's cloth sold at many hardware stores. Cut off a section of the cloth and wet it with water. Now use this cloth to scrub the stain. This is fantastic for removing calcium stains in a toilet.
Natures Miracle will dissolve the urine crystals
Lysol toilet bowl cleaner it is a blue gel squirt in potty for an hour wipe out.
It works really well.
Vinegar if you want to go the natural route, lime away if you want a commercial product.
I would use CLR on it
I'm serious, use white vinegar. Let the vinegar sit overnight on the calcium. Just pour a generous amount inside the bowl if that's where the calcium is and wait. It will dissolve like powder. Rinse and you're ready to go again. :)
We have 3 restrooms in our home and calcium build up used to be a problem. I spent hours trying to chisel, scrape, and use expensive products that did not work. I was told to try white vinegar and voila! Problem solved.
I even used it around sink handles by saturating an old washcloth (now rag) and leave it set on and around the calcium buildup. Works great for the coffee maker, dishwasher etc. Good luck!