First, ammonia in aquaculture comes from problems in the pond nitrogen cycle. As in nature, decaying animal wastes and excess feed (found in the pond bottom sludge) convert from organic nitrogen into ammonia. Ammonia can kill an aquaculture pond outright while still at less than 10 mg/L. Even at "manageable" levels, ammonia stresses the organisms which lowers feed conversion rates and weight gain.
Ammonia can be removed from water in several ways from greatest to least important
- Algae thrives when given ammonia as a nutrient
- Heterotrophic microbes use ammonia to fuel growth and make proteins
- Chemotrophic ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) exist in low concentrations in biological floc
- Check pond bottom sludge levels prior to stocking
- Ensure aerators are in working order
- Use the correct feed composition and feeding rates
- Stock at appropriate density
- Adding heterotrophic waste degrading bacteria from the start of the season helps (adding before you get highly polluted water is key).
- Organic wastes, including sludge, are consumed by microbes. This happens naturally, but often with high stocking density & feeding, you have waste buildup and start of problem anaerobic conditions (often seen as black sludge with hydrogen sulfide).
- Microbes under low oxygen conditions (pond bottom) use nitrate/nitrite as alternative electron acceptor - this prevents inhibition of AOB/NOB activity
- Microbes in quality products also help reduce pathogenic bacteria growth via competitive exclusion
- Beneficial immune stimulation by select probiotic cultures
- Promotes green algae (eukaryotic) organisms growth. Remember these microbes remove more ammonia from pond water than any other organisms.
Key point is to monitor the pond for pH, Dissolved Oxygen, Sludge Layer frequently. If stocking at high density, adding microbes early on in the grow out season will prevent pollution problems later in the season.