as others have said, the accordion bottles are bad news. You're far better off with a bunch of plain glass bottles. When I mix up a gallon of stock it goes into four quart sized glass bottles with poly cone caps. Developers like Dektol, D-76 and D-23 easily keep for the advertised 6 months in full bottles. I've had a bottle of replenished D-23 last over a year and a half.