Circulation systems for ponds, lakes, or other bodies of water using a flotation platform, dish, and impeller. One embodiment has a connecting arrangement between the drive motor and the impeller that permits the two to be easily and quickly coupled and uncoupled. The connecting arrangement also is designed to accommodate slight misalignments between the shafts. An arrangement to adjust and calibrate the depth of the inlet to the draft tube is disclosed. The system further includes solar panels that can be pivotally swung outwardly to open positions, angularly adjusted about a horizontal axis, and mounted to face toward the central axis of the flotation platform rather than away from it. Arrangements are further provided to monitor and control the components of the system including remotely from shore.