Originally Posted by irchowi
...So what I'm wondering is why anyone is using $20 better bottles when you can get $10 water coolers that are essentially the same thing?
The manufacture process is different for Better Bottles.
Part of resistance to oxygen permeability is from the composition/material and part is from the material's structure as manufactured ... and part, significantly, from the closure. Better Bottle actually uses a specific high pressure blowing/molding process that was designed to maximize the carboys resistance to oxygen permeability better than that of other PETE carboys (the ones from Absopure for example).
Also, the closure from Better Bottle is significantly better than others.
Common silicone or PVC stoppers are really not suitable for long term storage and are notorious for allowing in oxygen long term. As well, any closure using liquid over the long haul will gradually leach oxygen thru the liquid in the airlock.
The best against oxygen infiltration are something like the closure products from Better Bottles. Other things that work well are natural rubber stoppers or carboy-caps ... although with natural rubber, very old ones will eventually dry out.
The old, stinky black or red neoprene stoppers are also decent against oxygen infiltration ... it just the odor potentially getting into your product that seems to be a downside.
The better bottle system is really the hot ticket for bulk, long-term storage in a plastic carboy.