I’m thrilled to report that the experiment is on track and functioning as intended. This crude set up performs well even when air temperatures fall into the single digits. My only concern at this point is that I do not have enough fish in the tanks. That is not a result of my setup but just plain poverty. The early winter weather forced us to focus our efforts on caring for the other livestock and we couldn’t continue stocking the tanks. We should have had several hundred fingerlings by now. Hopefully we can start stocking again after the holidays.
I have noticed that while the water flow is not impeded by the low air temperatures, the air pumps are very much affected by the cold. In commercial operations aeration is accomplished by means of mechanical agitation of some sort, impellers at the water surface, paddle wheels. Tank culture is usually done indoors or if outdoors then in warmer climates. Fortunately as the air temp falls the air density increases making up for at least some of the diminished air flow. I have a couple ideas on how to fix this problem but the best one is to put a hoop structure over the water conditioner and main tank. It would be impractical to try and cover all of the tanks because of the fairly steep slope of the ground. It should not be necessary though as most of the air injection is done before the water flows to the downhill tanks.
Another important aspect of air pumps is that they require much less energy to operate than rotating motors. If larger fish are relocated to the pond though, it would be necessary to add one of these motors there. This is an important point I may have failed to mention. Once the limits of the system are reach, it would still be possible to increase production rates by using the pond. The pond also serves as an emergency relief point should all else fail.
While pond culture is common, for us it is not the best option because harvesting there is a whole other process and is very labor intensive. We prefer to net the fish from the tanks as needed. Once the next phase begins this spring, I will be able to determine the actual number or pounds of fish that can be raised with the given water flow rate.