# Water IoT Monitoring System for Aquaponics Health and Fishery Applications
## 3 Materials and Methods
### Analysis of Requirements for Aquaponics System  
The analysis of requirements for the aquaponics system has followed a two-fold methodology. The identification of the minimal requirements an aquaponics monitoring system should possess when optimizing for a low-cost monitoring system available for all markets and the identification of requirements needed to create an internationally competitive monitoring system. This methodology allows us to maximise the exploitative aspects of the outcomes generated in the project and optimize for the concrete system being addressed in the demonstration phase of the project. In this report, the two-fold methodology will be referred to as an \"ideal scenario\" and a \"minimal suitable scenario\", respectively. Figure 2 shows a conceptual simplified version of a floorplan representing an aquaponics system. It is composed by fish ponds, grow beds for vegetables, bio-filters and swirl filters, pumps and pipes to interconnect the whole system, and the points to connect the sensors to send information to the farmhouse. The ideal scenario will allow for per-pound metrics, per-grow bed metrics, and per-filter metrics for each sensor available in the system; however, this represents a significant increase in price for the final product. This kind of system is conceptually viable but economically not affordable. Thus, the next step in the trade-off for accuracy/price would be the use of four sensors, i.e., 2\(\times\) Type-A sensors and 2\(\times\) Type B sensors, explained later. The system will alert the farmer if there is an issue, the type of issue, and where it can be fixed; however, determining the best place to fix the issue might require an in situ investigation outside of the data monitoring health system. This is what we have coined as the \"ideal scenario\". The \"minimally suitable\" deployment would be to make use of two sensors (2\(\times\) Type A+B sensors). The Type A sensor is located immediately after the fishponds; thus, it measures the water parameters related to fish health. These parameters include the \(pH\), \(EC\), \(TDS\), \(DO\), temperature, \(NH_{4}^{+}\) and/or \(NH_{3}\), and/or \(ORP\), and these parameters should be measured in an ideal scenario. In a minimally suitable scenario, \(NH_{4}^{+}\) and \(NH_{3}\) could be substituted for \(ORP\), carrying out a trade-off between accuracy and cost. This minimally suitable scenario will allow the farmer to know if there is a higher \(NH_{3}\) or \(NH_{4}^{+}\) concentration. It is  
Figure 2: Simple aquaponics system floor plan. important to note that \(NH_{3}\) is toxic for fish and can cause death, but \(NH_{4}^{+}\) is not as toxic and can only cause death at very high concentrations. In addition, EC could be replaced by a cheaper and less accurate \(TDS\) sensor. \(EC\) measures the electrical conductivity of water, whereas \(TDS\) measures the level of particles dissolved in water, and both are good estimators of the number of ions present in water. This sensor also ensures that water reaching the fishponds is clear and compatible with fish health. Type B sensors are focused on providing the level of plan nutrients generated by the bio-filter to estimate the quality of the nutrients for the plants. Thus, it should provide \(pH\), \(EC\), \(NO_{3}\), and \(NO_{2}\) levels in an ideal scenario. In a minimally suitable scenario, \(NO_{3}\) and \(NO_{2}\) could be measured out of the data monitoring system while setting up the biofilter until it reaches expected levels of bacteria; then, EC will be used to estimate the concentration of ions (nutrients) in water. This sensor is also focused on determining the quality of the water being provided by the grow beds. Table 3 represents the different types of sensors and their associated monitoring parameters. The table also contains a combined sensor with all the parameters together to save manufacturing time. Table 3 shows the minimal viable set of metrics, and for the minimal viable set of metrics, there are other metrics indicated with *.