Your springs are most likely your problem. If that is your problem the Ess-13 will never work. The problem with a spring is they have a natural level according to how much pressure they have. This level will change with seasonal aquifer variation. If your spillway is higher than that level, water will go into the spring when the hydrostatic pressure is greater than the level of the spring. If and that is a big IF that is the problem, the only way to fix it is to drain and seal the whole pond with clay or a liner. Both are a very expensive propositions.
