It should be noted that in order to maintain the system with two pump heads these will need to operate at the same rate, as otherwise the pumps will either empty of flood the chamber. Setting up the system with a pump at the outlet may make balancing the media level in the chamber easier. If the customers are using multiple chambers in a series, it may be worth starting with a single chamber circuit as we have found levels are easier to balance in this situation.
We have found that positioning the chambers at a slight angle, with the thicker outlet tubing raised relative to the inlet tube, can often allow the inserts to remain submerged. If the chambers are being opened whilst the system is in use then we would advise that the upper inserts are opened before removing or replacing the lid, to ensure that the pressure within can equilibrate.