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Water-analysis kits are useful for practical aquaculture only if they provide equivalent decision-making as compared to standard water-analysis methods. This study used weighted Cohen's kappa (κ) statistics to compare management decisions made by farmers who used water-analysis kits (e.g., Seneye slide kit, Tetra EasyStrips, API test strips, Seachem Ammonia Alert, Salifert Profi test kit, and Hach dissolved oxygen (DO) and alkalinity kit) and decisions made by those who used standard methods. The decisions made by farmers were similar for water-analysis kits and standard methods, except for Tetra and API test strips, when measuring nitrate concentrations. The highest conformity between the two methods (κ-value = 1.0, P < 0.0001) was obtained with the Hach and Salifert Profi test kits (for measuring DO) and the API test strip (for measuring total hardness). The rapid, simple measurements by the kits appear suitable for use by farmers if they are properly maintained and manufacturer's instructions are followed.
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... WQS have been used to analyze various species of free chlorine, hydrogen sulfide and formaldehyde (Arsawiset and Teepoo, 2020), tetracycline antibiotics (Li et al., 2019), Hg (II) ions (Lan et al., 2018), Zn (II) ions (Takahashi, 2014), microcystins (Humpage et al., 2012), hypochlorite (Ballesta Claver et al., 2004), water hardness (Capitán-Vallvey et al., 2003) and microorganisms (Martins et al., 1997). The reliability of WQS for WQM was assessed against laboratory-based standard methods (Naigaga et al., 2016;Mosley and Donald, 2005;Bischoff et al., 1996). However, test strips lack selectivity of detection due to the random diffusion of chromogenic reagents in the detection zone in the presence of common interfering agents (Evans et al., 2014). ...
... The limited performance of the test strips for total alkalinity analyses may have resulted from the fact that the range of concentration of this parameter in Medjerda watershed has been often not high enough for assessing the reliability over their entire analytical range. Earlier comparison of the reliability of the WTS revealed that test strips generally gave a substantial agreement with the standard methods for total alkalinity (Naigaga et al., 2016). Nitrates test strips provide slight reliability in the 0-10 ppm NO 3 concentration range where one method indicated zero nitrates while the standard revealed measurable concentrations. ...
... The inferior reliability of test strips for nitrates compared to standard methods may be due to the presence of common interfering colloids agents (Forest et al., 2004). Other strips, such as API TM five-in-one aquarium and Tetra Easy TM six-in-one aquarium test strips, have been found not to agree with the standard methods for nitrates (Naigaga et al., 2016). The results show also that sodium chloridesensitive test strips are the most reliable for measuring a wide range of concentrations (0-7510 ppm) with the highest correlation parameters (PCC (0.962), R 2 (0.926), and α c (0.982)). ...
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... The limited performance of the test strips for total alkalinity analyses may have resulted from the fact that the range of concentration of this parameter in Medjerda watershed has been often not high enough for assessing the reliability over their entire analytical range. Earlier comparison of the reliability of the WTS revealed that test strips generally gave a substantial agreement with the standard methods for total alkalinity (Naigaga et al., 2016). Nitrates test strips provide slight reliability in the 0-10 ppm NO 3 concentration range where one method indicated zero nitrates while the standard revealed measurable concentrations. ...
... The inferior reliability of test strips for nitrates compared to standard methods may be due to the presence of common interfering colloids agents (Forest et al., 2004). Other strips, such as API TM five-in-one aquarium and Tetra Easy TM six-in-one aquarium test strips, have been found not to agree with the standard methods for nitrates (Naigaga et al., 2016). The results show also that sodium chloridesensitive test strips are the most reliable for measuring a wide range of concentrations (0-7510 ppm) with the highest correlation parameters (PCC (0.962), R 2 (0.926), and α c (0.982)). ...
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Mass balance principles are a cornerstone of efficient fertilizer use and can be utilized to optimize plant nutrition without discarding or leaching solution. Here, we describe the maintenance of closed hydroponic and soilless substrate systems based on mass balance. Water removed by transpiration is restored with solution that replaces the nutrients that were taken up with the water. The concentration of nutrients in this refill/irrigation solution is determined by multiplying the optimal concentration of each nutrient in plant tissue by the water-use efficiency (WUE; ratio of dry mass to water transpired). Optimal leaf nutrient concentrations are well established, but WUE in controlled environments varies widely and is less well characterized. Elevated CO2 increases photosynthesis and demand for nutrients, but partially closes stomata and reduces transpiration; so high CO2 dramatically increases WUE. The concentration of the refill/irrigation solution must be adjusted to account for a two-fold range of WUE, from 3 g L−1 in ambient CO2 in lower humidity, to 6 g L−1 in elevated CO2 in higher humidity. WUE and nutrient requirements vary during the vegetative and reproductive stages of growth, and adjustment of the solution over the lifecycle can be beneficial. Measurement of solution electrical conductivity (EC) is helpful, but if the solution is appropriate, low EC usually means healthy plants and active nutrient uptake. The ammonium to nitrate ratio is critical to pH management. We have applied these principles across multiple species and environments to achieve long-term, steady-state nutrient concentrations with no discharge or leaching of solution.
... For example, mobile phones with GPS, photography, and social media applications have proven effective in collecting data on the color and transparency of surface waters by citizens, as has been implemented in the River Chief Mechanism (Zheng et al., 2017). Simple and inexpensive water test kits, available from many pet stores or online retailers, are useful to small farmers when preventing water quality degradation in fish ponds (Naigaga et al., 2017). High-throughput sequencing of DNA extracted from water samples serves as a quick, cost-effective and standardized method for scientists and conservation agencies when evaluating rare and threatened species across a wide range of taxonomic groups (Thomsen et al., 2012). ...
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