I've used both 25L and 40L pots and recommend the latter. Don't skimp on potting mix. Buy a premium mix. Fortnightly feeding with a mixture of seaweed extract and fish emulsion will do them wonders. Sprinkle some sulphate of potash on the surface near flowering time. The biggest issue with pots is heat. I've tried painting the pots white and surrounding them with a cardboard box and stuffing straw between pot and box. Both work but the latter is better.
Hope this helps.

Same as Ray re size. Most of mine are 35 litre plastics from Kmart.
I use various soils and potting mixes and mixtures of both. Our soil yard sells a soil mix that is sandy and mixed with old cow poop. For most of my pots I have mixed approximately equal parts of this and premium potting mix togther.
I have one half wine barrel and that has the soil mix only. I find that they dont need as much water with some soil mixed in.
Mantis

Ok lads a translation is needed here. How many cm's in diameter is a 40 litre pot....given that the pot is round of course. Surely you cannot mean it would hold 40 litres of water, being that there were no holes in the bottom.
I have my sweet bite growing in a pot that is 40 cm's diameter. Is this large enough?
The plant has reached 6ft, is this odd? should I lop the top of it off. The stake is going to be too small if it keeps growing at this rate.
I have been feeding it charlie carp every couple of weeks, haven't tried seaweed emulsion yet.
It has hundreds of toms on it in varying stages of ripening, the children just pick and eat all the time.

I reckon the 40 cm pot would be about what I have. If I empty a 30 litre bag of compost into one there is still room for 5 or so more litres.
If you check out my home page, the ones I am talking about are the brown pots in the fourth picture. The green one is much bigger.

Thankyou for letting me see your home page. I would say that I have put my tomato in the right size pot. Thankyou Mantis