"No dig" in Pots

Does the level in your builder's bag drop at all?

Here's what looks to be The Eden Project's artificial soil recipe:

• 25 per cent sand waste from Cornish china clay mines
  
• 32.5 per cent composted tree bark
  
• 32.5 per cent composted green waste
  
• 10 per cent coal rich clay (lignite).
  

Surprisingly high in organic matter, though composted tree bark is fairly resistant to degradation. I wonder if they have to top it up every year. Currently they're doing more research into artificial soil mixtures in conjunction with the University of Plymouth.

I emptied the bag after two years and filled my raised bed in the greenhouse with it and has been in there for two years, the level does go down but so far I have just been filling up with seaweed, but intend adding course sand once the bed is empty as it looks a bit claggy
Thanks for the info regarding the soil makeup of The Eden Project