Shot in the dark here. I started getting a whiteish precipitate on the inside of my stock bottles of D23. Its like a scum only on the inside glass, the developer looks fine. I use replenisher and this never happened to the D23R bottles. The first time I thought it was a bottle contamination issue so I switched bottles. That seemed to work. The second time this happened with a new batch of D23 I switched bottles again but the next day the precipitate returned. Subsequently after this happening a third time I don't believe it's a bottle contamination issue...but not completely ruled out. To explore other issues I thought temperature fluctuations may cause the SS to precipitate out, but when I measured this the storage area only got warmer overnight by 8 degrees max never cooler. My third thought is the film. This started happening about the time I switched from exclusively using TriX to a combination of HP5 and Kentmere, and Double X. When using TriX exclusively black silver sludge would accumulate in the bottom of the bottle but with these other films I get no sludge. So I was wondering if anyone could confirm if this is possible, like a sodium sulfite silver nitrate reaction causing the precipitate from different film stock?. Image of one of my D23 bottles with precipitate as cloudy surface scum.