Mechanical aeration can be acheived one of five ways:
1. Naturally
2. Surface (agitators, paddlewheels, fountains, horizontal agitators/aerators, spray nozzles, venturi, solar surface prop driven)
3. Bottom diffused
4. Linear (Bubble Tubing)
5. Hypolimnetic (Without disrupting the thermocline)
Bruce, let me collect my thoughts about the comparison of bottom diffusion vs. circulators, but off the top, it comes down to energy required to move a certain amount of water.
