Also, a pond management company has a greater level of expertise. They not only know what to do, and how to do it, but WHY to do it using the best management practices. As long as the pro knows your goals and sees your vision, that company is trained to help you achieve those goals in the timeline you expect as well as inside the budget you have.
Professional pond management companies, as long as you choose one that fits into your mission, can go a long way to getting your pond as you want it to be.