@prawnmaster I did use venturi devices for a 1ha ponds in 2015. From oxigen input POV was much cheaper setup pipe lines and pumps, than paddleweals. But it was a headacke to manage the maintenance of venturi setup and the mud development at the bottom.

The air injection was setup in two separeted systems. From the pond boarders, using a main pipe line with a 2hp submersible pump, were the venturis distant from each 20m and 8 x 1hp pumps with 10m long arms (with 5 venturis), spread at the pond to help develop the centrifug vortex.

The mud settlement increase in the areas beside the submersible pumps and pipe stands for the venturi arms. We did more effort siphoning in the first crop. The second crop I did add 4 x 2hp injectors to bring the mud to the center.

If your wind is not so strong, you can use injectors with no problem. But if your wind is too strong frequently, the best way to don´t get your production limited or keep people syphoning all day, will be a mixed aeration between injector and paddlewheals.

In open ponds with high densities, the main reason for strong aeration isn´t only the oxigen input, but also the water movement to get rid of mud. In areas where the water salinity can increase due evaporation, the best way to reduce the wind impact at the pond water surface is builting a 1.5m shadow net wall/cover all over each pond or set greenhouses to keep the ponds isolated.

If the salinity don´t get higher than 60ppt and the evaporation rate is below 10mm/day, use air injectors. If the salinitiy comes often above 80ppt and the evaporation rate is greater than 10mm/day, try to cover the ponds to protect against wind and sunlight. Changing the aeration system won´t help too much if you are worry about salinity.

Fabio

Anyone with info on standard oxygen transfer rate and SAE comparison paddlewheels versus venturi injectors?