Aeration diffusers come in various designs, each suited for different water treatment needs. Here are the main kinds:

1. Fine Bubble Diffusers: These create small air bubbles to efficiently transfer oxygen into water. They're ideal for processes needing high oxygen levels, such as in wastewater treatment plants. Common types include:

2. Disc Diffusers: Round and flat, made from flexible materials, they spread tiny bubbles throughout the water.

Tube Diffusers: Long, cylindrical shapes distributing fine bubbles, made from similar materials as disc diffusers.

Coarse Bubble Diffusers: Producing larger bubbles, these are less efficient at oxygen transfer but great for mixing water and preventing sediment buildup. They're simpler and tougher, making them easier to look after and less likely to clog.

3. Medium Bubble Diffusers: These strike a balance, making bubbles that are bigger than fine bubble diffusers but smaller than coarse ones, offering a mix of oxygenation and mixing benefits.

4. Membrane Diffusers: A type of fine bubble diffuser that uses a porous membrane to release air, preventing clogs and evenly spreading bubbles.

5. Static Tube Diffusers: These tubes mix air and water without moving parts, using the water's own motion to draw air in, suited for places where simple aeration is needed.

The choice between these depends on what's needed for the water treatment process, such as how much oxygen is required, the depth of the water, the kind of wastewater, and budget constraints. Fine bubble diffusers are often preferred for their oxygen efficiency, but coarse bubble diffusers might be chosen for their mixing ability and lower upkeep needs.