The other thing you can consider doing is run a single line diffuser to deepest main part of the pond to mix the main portion of the pond. Consider enlarging this single diffuser to 3 or 4 heads for more volume mixing per hour. Depending on the pond size, shape & average depth of the pond (morphometry) the mixing by a larger diffuser may turnover an adequate portion of the pond for acceptable results. Note most water will usually naturally mix to around 5-6ft deep which means you do not really need to mechanically use diffusers in these areas.
