I just got a new hatchling who's about 130-150 grams give or take and I set him up in a 6 qt tub which fits a water dish and an appropriately sized hide very nicely while still allowing for enough room for the snake to move around quite a bit (which is good because the little guy loves to roam). My last snake lived in the same tub until she was about 20 in. long (sorry, I don't remember her weight at the time). By that point I could no longer fit the hide in there with her and I'm certain that she was rather cramped but I was waiting on getting a 15 gallon tank to move her into.

I might be wrong but I think the 12 qt is slightly taller than the 28 qt if I recall correctly but the 28 qt has more length and width to it.