16 Oct 2019
When Dissolved Oxygen Drops, When do Farmers Take Action in Latin American Ponds?
Written by Zach Stein

When we first began Osmo Systems, we spent a lot of time in Asia with farmers there learning about their farming methods and some of the issues they had. But as time went on, we began spending increasing amounts of time in Latin America and had to start at the beginning in some ways given how different ponds and farms are between the two regions. 

We wanted to know if dissolved oxygen drops, at what point do farmers take action? And what action do they take? 

Our Survey

We posed the question to 10 farmers of various sizes over WhatsApp over a period of a few days. We wanted to question to be relatively straight forward and easy to answer. We initially tried with a longer email but found we got a better response over WhatsApp. 

Results

See below for our results. There is a good amount of consistency with a few outliers. The farm that takes action at 5.0 mg/L is operating at a higher stocking density and therefore has to be more responsive to dissolved oxygen.

Takes First Action atTakes Second Action atActions Taken
2.51.8Pumps, then h2o2
3.0h2o2
2.0Pumping or h2o2
2.72.0Pumping, then h2o2
5.02.0Maybe h2o2, definitely h2o2
2.0h2o2
3.0h2o2
3.0h2o2
3.02.0H2o2, depending on stocking density

Conclusions

From our results we saw that farmers generally look at 2.5 – 3.0 as a initial place to start paying attention to dissolved oxygen. The response would either be adding hydrogen peroxide or pumping in fresh water to the pond. Then if DO continues to drop, they take further action to stabilize it and bring it back up. 

We do wonder if this is a “best case scenario.” In our travels in Latin America we have had a number of conversations after a few beers with farmers and we sometimes find they push their DO a bit. We’ve heard of farmers waiting until their DO was at 1.5 mg/L to take action. 

How about you? When do you take action on your DO?