Handheld probes for managing water quality on your farm

The Ministry of Agriculture and Saskatchewan Crop Insurance Corporation have free testing available at regional offices across the province for water quality on your farm. If this option does not work for you, consider purchasing a water meter to test livestock water sources on your operations. This can be a great option to do some at-home screening of samples, but make sure to visit a regional office if samples are testing in a range where a second check is required.

Purchasing a handheld water testing meter can be overwhelming. A quick internet search will generate results of probes ranging in cost from $10 to over $1,000. Each probe may have different units, capabilities and maintenance requirements. Deciding on the correct one for your operation can be challenging.

To help narrow down your search, here are some things you should consider:

• The most common parameters that handheld probes can measure are electrical conductivity (EC), total dissolved solids (TDS) and water temperature.

• Typically, the units for conductivity are either uS/cm (microsiemens per centimetre) or mS/cm (millisiemens per centimetre) and TDS is either ppm (parts per million) or ppt (parts per trillion).

• Specific conductivity is the measurement that livestock and feed extension specialists use in the regional office when probing your water source. Specific conductivity is the quickest predictor of the water quality. The units that specialists use is uS/cm, so if you want to compare to the lab quality probe in the office, choosing a probe that measures in the same units would be valuable.

• TDS are often referred to when measuring water quality. However, meters that only display TDS can often be problematic since the TDS displayed on these meters is generally derived from the conductivity using a conversion standard that may not accurately reflect the sample. Probes may show a 50 or 70 on the screen; indicating the conductivity is being multiplied by either 50 per cent or 70 per cent to calculate the TDS number. Livestock and feed extension specialists in Saskatchewan have analyzed thousands of local samples and have found that for this province the conversion factor is closer to 80 per cent province-wide, and averages 89 per cent in the southern half of the province. In many cases, therefore, the water meters that are predicting TDS are severely underestimating the actual TDS value.

• Like most things, you often get what you pay for. In the specialists’ experience, the cheaper the probe, the more inaccurate it is on marginally poor water. Specialists often recommend choosing a probe in the $75-$100 range to have a few more options and a little more consistency.

Once you have purchased a probe, there are a few tips and tricks to keep it working at its best.

• Always rinse the probe with clean (preferably distilled) water after each use. Minerals can build up on the sensor of the probe, potentially causing inaccuracies in the testing parameters.

• The Ministry of Agriculture regional offices have calibration solution available to check your probe’s accuracy. Seeing how your probe compares to different known solutions will give you a baseline for determining when water is either safe or not recommended for use, and when that sample needs to go for a more thorough analysis.

• With time, your probe may not test water quality accurately. New tips can be purchased for most probes. It’s important to occasionally track and monitor your probe results compared to a lab result and replace the probe or the tip if the results are no longer consistent.

Definitions:

Electrical Conductivity – measure of the water’s ability to pass electrical flow, directly related to the concentration of the ions in the water.

Specific Conductance – the conductivity measurement at (or corrected to) 25C to standardize the reporting method of conductivity readings.

Total Dissolved Solids (TDS) – the combined sum of all the ion particles that are dissolved in the water, including the ions associated with salinity and dissolved organic matter.