I only make enough to fill a 1 oz spray bottle. I dont store excess. You can, but Im no chemist so I dispose of anything left over. It is advised in every sts guide I've ever read to use RO water. That's all I've ever used. When dealing with dangerous and toxic chemicals I make a point to follow the directions to the letter. Nothing should turn black. Im not sure what you mean by "dumping old water" or "rinsing". I just want to be clear that when making fresh sts spray, the final mixture should not turn black or any other color. If it does, something went wrong and I would immediately dump that mixture. Sts or the separate parts of A and B stored for long periods may change color.. But that's not a good sign.hi Proph! are you usually using all your solution or keep some? Looking at what I have stored, I think the silver can turn things black when there are some impurities and non distilled water is used. My Silver solution is clear, and so is my Sodium, but I have a char where I dump old water or after rinsing and that solution is dark brown, like watered down coffee.