. . . make a 26.5 liter (7 US gallons), or larger, PET carboy? We are frequently asked, "Why not make larger PET carboys; they would sell like hotcakes?" The simple answer is that we would love to make them, if they really would sell like hotcakes. Making BetterBottle carboys involves highly sophisticated technology and production machinery and keeping the price competitive requires large production volumes and extremely efficient shipping.
There are many reasons why BetterBottle carboys have replaced glass, but our customers rank the top three as: 1) Safety, 2) Weight, and 3) Ease of cleaning, in that order. 22.7 liters (6 US gallons) of wine or beer weighs approximately 22.7 Kg, (~50 lbs) and 26.5 liters (7 US gallons) weighs approximately 26.5 Kg (~60 lbs). Winemakers and brewers cheered when 22.7 liter BetterBottle carboys, weighing just 0.68 Kg (1.5 lbs), replaced 22.7 liter glass carboys that weigh about 7.7 Kg (~17 lbs), because 30 Kg (~ 51 lbs) is as much as most people are comfortable lifting onto a counter or shelf.
Empty carboys cannot be nested the way pails can and the dimensions of BetterBottle carboys are selected with a great many parameters in mind, besides the obvious requirement for functionality. The carboys are sized so they can be efficiently palletized and so the pallets will fit into all kinds of shipping containers and trucks, with a minimum of wasted space. They are also sized so bulk-pack cartons are a just below the "large box" point at which parcel carriers charge extra. Making BetterBottle carboys a fraction larger than they are could increase their store-price significantly.
From everything we can determine, there will not be enough demand for larger carboys to offset significantly higher production and shipping costs, and they will fail as products. That being said, BetterBottle is busy working on a practical solutions that are compatible with existing BetterBottle carboys (keep checking back).
. . . make a PET conical fermenter? Large-scale, conical fermenters, used in conjunction with filters, are definitely effective; however, on a small scale, things do not work out so well. We tested a prototype of a transparent, PET conical in our development lab and we saw what cannot be seen in opaque, or translucent, conicals. Fine particles settle on the sloping walls of the conical section and remain "stuck" there, until the liquid level reaches them during racking. Then, they contaminate the clarified wine or beer. Racking was not nearly as clean as it is with our standard BetterBottle carboys and racking adapters. There is a reason for drawing clarified wine or beer from above the sediment during small-scale racking. Nevertheless, a conical made of our PET would have many advantages compared to conicals made from polyethylene, polypropylene, or polyvinyl chloride. The PET conical would be essentially impermeable to oxygen, would not stain, would not add or transfer flavors, would be transparent, and would be a great deal easier to clean. Unfortunately, a PET conical would also cost more, making it quite impractical in view of the fact that BetterBottle racking-carboys perform better in any case.
. . . make a PET pail? Pails made from plastics that are permeable to oxygen and that scalp flavors and stain certainly are not ideal as primary fermenters. So, why doesn't BetterBottle make a PET pail? Because it would be so prohibitively expensive, using existing technology, that stainless steel pales would be cheap by comparison. That being said, BetterBottle is constantly looking at options for making the equivalent of a Better Pail and the technology may become available in the not too distant future (keep checking back).