"Cheap" is a very relative concept, and greatly depends on the time-frame involved. The "cheapest" per-application treatments usually turn out to be the most expensive treatments (cumulatively) over an extended period of time - especially when labor is factored into the equation.
Also, many variables will dictate your available treatment-options - regardless of their expense or economy (i.e. general pond design, flow-dynamics, fish species present, relative plant biomass, aeration/O2 levels, etc etc).
IMO, you need more than a forum-based assessment to yield proper guidance. In what part of MO is the pond located?
