Simon
Does the design have one or 2 bakki showers? I'm guessing 2 or a double sized unit?
I would look at having some solids removal on each bottom drain independently.
Have a look at what Maurice has done with static kaldnes in 2ft vortexes at
http://www.koi-uk.co.uk/mechanical_f...capable_of.htm . You could have one of these units on each drain line and then pump to the showers.
I presently run a 2ft 'vortex' with a vertical sheet of fine matala matting to stop solids prior to 2ft chamber of submerged BHM and a 3tier bakki shower.
This gives excellent quality water and simple maintenance.
Mark