Surgery. You will need to put the spa and edge and enter into the base. If they are leaking at the plumbing connection, there would be evidence of the leak at the fittings. Because the drains are connected to the pumps, are you sure the orgin of the water loss is not in the EQ area. You say it drains down to the level of the suction fittings. Do you have any indications of water backside, left side, right side base, or in the EQ area?