There are a couple statements in this topic that I want to discuss.
"Alot of people don't realize or accept that ammonia kills happen every day. The aerator above should eliminate that, but you can't be too cautious."
"I would like to see a unit that chops and sprays up into the air instead of bubbling. This would help so much with the removal of ammonia and other obnoxious gases."
The surface aeration unit may help reduce the chance of fish kills but it will not directly reduce the amount of ammonia in a pond.
AMMONIA - Background. By far, most of the ammonia is produced in natural ponds by bacterial decomposition of organics. Ammonia produced by higher organisms is a small percentage of the total production. When the ammonia is produced or released it combines / attaches to water molecules. His is then called un-ionized ammonia (NH3). Un-ionized ammonia when present in higher concentrations is the form that is stressful and toxic to aquatic life. Un-ionized ammonia is more toxic at warmer temperatures and in waters with higher pH. Increasing the salt or salinity concentration decreases the toxicity of ammonia.
MYTH - It is often thought that ammonia is released from the water during aeration; bubbling or spraying water into the air (ammonia striping). Stripping ammonia from the water molecules can be done but not in normal pond conditions. If ammonia could be removed from the water by aeration (bubbling or splashing) then fish haulers who use violent aeration for transporting fish would never have problems with ammonia toxicity. Ammonia toxicity is a very big concern for those who haul or hold fish at high densities.
FACTS � First to convert all the ammonia to the gas form (NH3), the pH must be adjusted to above pH 12. Then, high volumes of air are added to the water to cause changes in the partial pressure ratios. Then a long contact time is necessary during the air-water splashing to create a large air-water interface for diffusion of air in and ammonia out. If the water is to be reused for aquatic life the pH of 12 has to be readjusted back to normal levels (pH 6-8). A quote from Water Quality in Ponds for Aquaculture (Boyd) � Surface aeration (2kW) for 24 hours in 50 cu meters of water at a pH of 8.5 did not remove ammonia.� We know know why.
Ammonia (un-ionized) is removed from natural waters primarily by denitrifying bacteria and absorption by plants, especially phytoplankton.
The second point I want to briefly comment on is the quote:
That unit is a 1/2 horsepower 220 volt unit surface unit that sprays up 6 foot, and it pulls from 4 foot deep.
If the surface aerator pulls water from 4-4.5 ft deep, what will the water quality conditons be like in the remaining bottom water in this test pond (bottom layer 3ft to 4 ft thick)? During summer heat and intensive high protein feeding, associated manure production and lots of fish biomass, the deepest water layer will definately become anoxic (without oxygen). During anoxic conditons lots of bad water quality things develop in this deep bottom layer of water. This degrades water quality can possibly jeopardize the overall health of the fishery. I contend that "surface fountains" have much better overall results when used in ponds 3 to 5 ft deep. For aquaculture ponds deeper than 6 ft, the bottom, diffused air methology would produce better results. Bottom air diffusion combined with surface aeration would be the ideal situation to have in a high biomass, aquaculture pond.
