How much bones can be used in an 11 liter stock pot?
2kg of veal bones cut up for stock use from your butcher should need around 5 litre of water to cover.  If you use more then you're just thinning the stock and that'll mean you need to reduce it more later to get the same flavour you would have had if you started with the correct amount of water.  

Why does this matter you may ask...well, along with the longer reduction time you'll taste changes to the flavour more as time goes by.  You're cooking it longer and the heat changes things, sometimes for the bad, sometimes for the good.  Mainly it's just wasted time reducing something that didn't need to happen.

When all is said and done after simmering for around 6 hours, you'll end up with about 3-4 litres of quality stock if you went with a 2kg:5L ratio.  

If you use more water to start then you'll end up with more stock but of low quality.  Then you'll spend your time reducing the stock down until it starts to taste like the stock that you could have made with 5L of water.