I have some scary practice in this. the man was right. it's variable home to home based on conditions, dilution etc but able to be replicated in small scale if wanted.
not that this eliminates all sourcing for souring but it's certainly repeatable 1000% for sure this almost killed my tank once.
skip to the save...leaving all stored water open capped, for evaporation, and just topping off 100% fixed all fouling. it's oxygen related, biotic, not chemical beyond rotting organisms in the water which are dealt with by keeping oxygenation. Motion isn't even required, my containers simply sit open topped. the water could easily go a month I've done it multiple times. my vase is one gallon, a change bottle is 5 it goes a month in between all fills the same mix of water. sometimes longer, never spoils.
it dawned on me that we maintain a biome in our water change containers. if you keep things capped, then these communities die off due to lack of 02 in about that much time dumping in old capped water was the #1 closest I ever came to killing my 16 year old reef vase. I poured the water in uncapped without smelling, it caused clouding, instant closing of corals, migration of all microbenthic animals like brittle stars out and up the top of the vase they literally crawled out.
now that I keep all storage containters of sw open capped, and top off before use, this has never happened again. the organic brown slicks at the bottom of the container are a mini biome. it's actually not a big deal to dry them/empty container and rehydrate...what's bad is capping off/no o2.
if you let your change buckets dry out and refill them, castings of previously anchored organisms get rehydrated and put back into suspension. you gotta breathe all that vs restrict it.
it smelled like doom rotten eggs when I sniffed the water. I knew at that point, about 2008 ish, to NEVER cap storage water we maintain the open biome.
to replicate in small scale, get two scummy water change 5 gallon containers that's been used a while. has real scum brown on the inside bottom, something that fizzes like nuclear uranium if peroxide is poured on it (compared to no action from a brand new bucket)
keep one capped off with new change water for one month.
keep the other open topped one month, rarely topped off.
smell the two at the end
