Pond Boss Forums AERATION Systems questions Pond areation.

Bottom diffused aeration does definitely have pros and cons. IMO many more pros than cons depending on ones GOALS..

Bottom aeration has a complex interactive affect on pond ecology. To briefly address your specific query, (why is it beneficial?).
and "If it wont help with algea". Actually - bottom aeration as noted below may help algae grow better, lot less. Numerous experiences have shown where aerated ponds can at times grow more algae. This can be a good thing for many reasons.

When most ponds are thermally stratified and the illuminated zone is shallow (0.5"-36") all the pond bottom areas are first to lose dissolved oxygen(DO) due mainly to all the various forms of bacterial decomposition. This relates back to measuring how deep you can see the white object (Secchi disk).

Bottom diffused aeration is designed to cheaply move using air lift technology high volumes of the low quality water from the bottom areas to the surface where "bad" water is degassed, dissolved oxygen (DO) is added in various ways, and the upwelled decompositionally and chemically created dissolved nutrients are made available to all the plant life in the illuminated part of the water column. Again a need for 'white object' measurement.

In actuality and IMO the added nutrients that the aerator brings to the illuminated zone can and does stimulate algae and plant growth from the nutrients that develop from the numerous forms of bacterial decomposition especially in the deep bottom areas of the pond. The pond bottom areas may or may not be aerobic where if aerobic, the decomposition is 'fast & clean'. Anaerobic decomposition has no DO and those areas have basically no normal DO dependent life forms including the aerobic bacteria. Anaerobic decomposition is very slow and 'dirty'.

The amount of algae and plant life that develops in ponds is highly dependent on the amount of the historical nutrient accumulations that have occurred to that pond. More dissolved nutrients feed more plants. Nature's Law. Do the research.

IMO Aerators that are sold to reduce or eliminate algae are sold by sellers or promoted by those who are uneducated informants that do not well comprehend the complexities of aquatic limnology and aquatic ecosystems.

To be completely fair and cover more bases there are a few rare, special cases where bottom aeration can help reduce some special types of algae problems, however these cases are IMO very rare and not the normal conditions that occur in most all ponds. Unused available nutrients basically cause excess plant growths. Various nutrient balances are what feed various types of algae and plant problems.