Does anyone know what the expected shelf-life of should be? I'm talking about a solution in the 10% range. Also, any idea on how long is might last when filled vs. repeatedly open and partially filled, as would be the case with a solution used for daily use. I'm assuming, of course, a tightly capped amber bottle.(posted 8362 days ago)Any ideas on extending the working life of the solution--an additive that might prevent it from combining with carbon dioxide when exposed to air, but would not alter its characteristics?