Beyond Oxygenation: Less Algae and More Stable Biofiltration at a Danish Fish Farm
Key observations at Aarup Mølle: Less algae growth in the nanobubble-treated pond, reduced biofilter fouling, fewer cleaning hours and more stable biofilter operation. Oxygen saturation of approximately 125% was measured at pond inlets following installation.
At Aarup Mølle Fish Farm in Denmark, operators reported less algae growth, reduced cleaning needs and more stable biofilter operation after our partner TECHRAS Nano integrated Moleaer nanobubble technology into the facility's return-water system.
The project also documented oxygen saturation of approximately 125% at the pond inlets, compared with approximately 78% previously measured at the biofilter outlet.
Together, the findings offer a practical example of how nanobubble technology can support aquaculture oxygenation while contributing to broader water quality and operational objectives.
A visible difference in algae growth
One of the clearest observations came from two ponds operating under comparable conditions.
Ponds 3 and 4 were started at the same time. Pond 3 did not receive nanobubble-treated water, while Pond 4 did.
The difference was visible: Pond 4 showed noticeably less algae growth than Pond 3.
The parallel comparison provided a practical way to observe differences in algae growth under similar operating conditions. While the results are specific to this facility, they highlight an additional water quality consideration beyond oxygen saturation alone.
Higher oxygen saturation and more stable biofilter operation
The project examined how Moleaer oxygen nanobubbles performed when integrated into the fish farm's existing return-water system.
Before installation, return water leaving the biofilter measured approximately 78% oxygen saturation. Following installation, measurements at the inlets to ponds 4–9 reached approximately 125% oxygen saturation.
These measurements were taken at different locations in the system and should not be interpreted as a direct before-and-after comparison at the same sampling point.
Beyond oxygenation, operators reported:
- Less biofilter fouling and clogging
- Fewer cleaning hours
- More stable biofilter operation
Biofilters depend on biological processes influenced by water quality and oxygen availability. While the project did not independently establish the mechanisms behind these improvements, the observations show why oxygenation and biological water treatment performance are worth considering together.
What can aquaculture producers take from these results?
The Aarup Mølle project demonstrates how nanobubble technology can be integrated into an existing aquaculture water treatment system, with observations extending beyond oxygen levels alone.
For fish farmers evaluating oxygenation and water quality technologies, the project illustrates the value of considering operational factors such as algae growth, biofilter stability and cleaning requirements alongside oxygen measurements.
Moleaer works with aquaculture producers and technology partners to integrate nanobubble technology into a range of water treatment and oxygenation applications.
Explore Moleaer nanobubble technology for aquaculture, or connect with our team to discuss your facility's water quality and operational needs.
About the project
The Aarup Mølle project was carried out with support from the Henrik Henriksen Foundation. TECHRAS Nano supplied and integrated the nanobubble system, while BioMar participated in water quality monitoring.
This article draws on project findings originally published by the Danish Aquaculture Producers' Organization (DAPO).
Read the original Aarup Mølle project article.
Related research: Explore Dalhousie University's research on geosmin in RAS using Moleaer oxygen nanobubbles.
