Monitoring Systems

Monitoring is the basis for safe farming around the clock - whether the site is an earthen pond, raceway, net pen or full RAS. Without knowing what is happening in the water, you only react when the fish already show stress. With the right measurements, problems can be caught early: falling oxygen, a sudden temperature swing, a stopped pump, a full settler or a failed intake.

What always has to be measured

Whatever the production system, two parameters are practically indispensable: dissolved oxygen (DO) and temperature. Oxygen drives respiration, growth and survival - and changes quickly with feed, density, algal blooms, ice, pump failure or heat. Temperature drives metabolism, oxygen demand, immunity and the species comfort zone (e.g. Arctic char vs tilapia). Without some form of measurement of these, you are flying blind.

How you measure differs a lot. On a simple pond farm, a handheld DO/temperature probe a few times a day, plus eyes and experience, may be enough. On a commercial RAS you expect continuous sensors, PLC/SCADA, trends, SMS/email alarms and often redundant measuring points. In between - raceways, semi-flow-through, net pens - sites often combine spot checks with fixed sensors at critical points.

Differences between production systems

Ponds (mud / earthen ponds)

Large volume, natural primary production and strong day-night swings (algal photosynthesis raises DO by day; night risk of low DO). Measurement often focuses on DO and temperature at surface and depth, Secchi depth, and sometimes pH/alkalinity. Continuous sensors become more common at higher density, but many farms still rely on handheld checks, night watches and aeration started manually or via simple DO switches.

Flow-through and raceways

Water quality is driven strongly by intake flow and source condition. It is important to track temperature and DO on inlet and outlet water, plus flow (too little flow means oxygen risk and ammonia risk). Handheld checks can suffice on small sites; larger raceways and hatcheries often have fixed DO/temp sensors, flow switches and alarms on pump or intake failure. Solids and turbidity from the source may need turbidity or simple optical checks.

Net pens / cages

Fish live in the surrounding water body - measurement is about understanding the environment around the pen, not a closed loop. Typically: temperature profiles, DO (especially in summer stratification, algal blooms or ice), sometimes current, salinity and weather. On modern marine sites, buoys, underwater sensors and feed/camera monitoring are common; simpler lake cages may still use daily handheld checks and observation. Alarms for low oxygen or storms are more "environmental warning" than "pump trip".

RAS and semi-flow-through

Here monitoring is a process-safety issue. The system is tightly coupled: pump failure, biofilter trouble, rising CO2 or low oxygen can escalate in minutes. Standard is continuous sensors for DO, temperature, pH, often ORP/redox, level, flow and pressure; plus 24/7 alarms to staff. SCADA/PLC controls oxygen, valves and emergency modes. Spot checks (TAN, nitrite, nitrate, alkalinity, CO2) complement - some online, many still lab or handheld kits. The higher the reuse, the more critical the measurement becomes.

From handheld checks to SCADA

• Handheld probe / kit - cheap and flexible, but depends on routine and night staffing.
• Simple loggers and alarms (DO/temp) - continuous trend without full automation.
• Fixed sensors + PLC - automatic oxygen control, pump trips, level protection.
• SCADA/HMI with SMS/email/app - overview, history, remote alarms, multi-user.
• Integration with feed, cameras and AI - predictive alarms and optimisation (see AI section).

Typical measuring points on more advanced farms: DO and temperature in tanks and critical return lines; pH in the biofilter loop; flow and level in sumps; alarms on power, emergency power and oxygen reserve. Calibration, sensor placement (dead zones vs representative mixing) and spare sensors matter as much as "having a sensor".

The potential ahead

Better monitoring is not only fewer emergency trips - it enables higher density with maintained welfare, lower feed waste, faster troubleshooting and documentation for permits and customers. Data from DO, temp, flow and feed can link to growth models, energy control and early disease warning. Remote monitoring cuts the need for constant presence on distant pens or inland sites, while responsibility still requires someone who can act when the alarm sounds.

The potential is greatest where risk is fast and value high: RAS, hatcheries, high density and species with a narrow temperature window. But pond and cage farms also gain by moving from handheld-only checks to at least continuous DO/temp with alarms. The next steps - digital twins, AI feed control and automatic oxygen/flow optimisation - always rest on the same base: reliable measurements, especially oxygen and temperature.

TyrFlow (DABCE™)

DABCE TyrFlow™ is a triple-redundant sensing system with edge computing - developed among other uses for aquaculture, where reliable measurement and fast local processing are critical. Three independent measuring paths and computation near the sensors give more robust data, fewer false alarms and continued function even when cloud connectivity is limited. Contact DABCE for more on TyrFlow in farming, RAS and other demanding water applications.