what containers should I use for aging?

I would strongly advise you NOT to use the polyethylene type barrels for long term bulk aging. I have never used wooden barrels and from the comments I have seen on here it is fraught with possible problems -- especially for the small time home winemaker. I have never used stainless steel but certainly some of our US winemakers do use them. I have 8 x 23 litre glass carboys for my bulk aging and about 30 x 1 gallon ( imp). I used to have over 60 1 gallon jars but they occupied to much space! The 23 litre glass jars are readily available from your local home brew store complete with a cap which allows insertion of fermentation locks. You can also buy a suitable carrying handle which is necessary. ( see below)

The trouble with the"plastic" carboys is that in the long term they will admit oxygen to your stored wine. They also are very susceptible to off flavours being admitted to the wine. I do use them for fermenting in but transfer to glass once it is complete for bulk aging.

The disadvantage of the 23 litre glass is that they are very heavy especially when full -- over 60lbs and you should think carefully where you are going to store them

HTH

All of the large glass carbouys I've seen have been tulip shaped with a long stemmed mouth, hardly optimised for space, which I don't have a great deal of. After a bit more hunting, I discovered

which sell a 30 and 50 litre stainless steel bin that looks like it might be suitable. They also do a better shaped glass carbouy than I have previously seen, but they prefer not to mail order these items. However they are in county Durham, and a friend regularly drives there, so I'll pick some up next time he does. As for weight, said friend has arms like tree trunks and seems to be immune to the physics of weight and inertia. He also likes my wine.

The 23 litre carboys I use are not tulip shaped but upright with a flat shoulder and short neck. They are, I believe made in Italy. The ones you mention which, if they are the same as I think, come in a plastic basket and have a very long neck and have a quite wide maximum diameter --- and are just not very good -- even the neck is very wide and difficult to stopper. You don't say where you are but there is a very good on line Home brew shop which is based in Aldershot.

but they will not sell glass products on line.

or just do a search to find one nearer to you. There are lots of them around. Very few, if any on line shops will sell glass anyway!

If you want to go with steel make sure you are buying food grade stainless steel. Any other steel is not suitable for wine making as it will transfer compounds into your product.

I know of several wineries that will store upto 2500L in polyethelyene tanks for short durations ( less than a year) but longer terms are always done either in oak barrels or food grade steel. Further more they always but a CO2/N2 or Argon/N2 gas mix in the head space of the tank frequenlty to keep the O2 out.

Pinky made a note of saying air transfer through plastic which is true but he should also beaware that this occurs in oak barrels as well.

You could contact a labratory supply company and see if you could order lexan containers. Lexan is a plastic that has no taste or air transfer and is used regularily as lab stock bottles or hiking water bottles under the Nalgene name.

It could be done but you would realy have to supervise the barrels to make sure they aren't oxidizing too fast.