Asmodeous,
I do not know the 'bio-load' of the Wet/Dry - I couldn't get Amiracle's web site to open, but try the link here and see if you can find the information you require:
http://www.amiracle.com
The dimensions are posted above, and in the pictures you can see the bio-ball chamber is approximately half of the total volume.
Hope that helps.
Ryland