Abstract: In the aeration panel structure described in the specification, a porous membrane is mounted on a flat plate with peripheral hold-down strips secured at spaced points to the plate and a foam tape having adhesive on both surfaces is interposed between the plate and the membrane and between the membrane and the peripheral hold-down strips to retain the membrane in place and assure a good seal with the support plate. In addition, middle hold-down strips are provided to prevent billowing of the membrane and, at each end, the middle hold-down strips extend above the peripheral hold-down strips to assure air distribution beneath the membrane. Adjustable anchor bolts are provided to mount the aeration panel structure to the bottom of a liquid container.