I recently spoiled myself by buying a water quality testing kit from Water Rangers. While I was working at UofT’s survey camp, teaching water and environmental science to civil engineering undergraduates, I had the opportunity to compare the Water Rangers kit to the YSI Probe, a conventional piece of equipment for any scientists working in water quality.
Water Rangers started up when Kat Kavanagh won the AquaHacking competition in 2015. Kat’s goal is to bring knowledge and data about water to everyone. She put together a range of items that can test water quality, but are easy to use, and significantly less expensive than the scientific alternatives. The whole kit costs $350.
YSI is a company that develops and provides scientific monitoring equipment. Their device consists of multiple probes connected to a handheld computer. Measurements are very precise, but the probes require regular upkeep and calibration. I don’t know the exact cost, but it’s somewhere north of $5,000.
This is a breakdown of the different water quality parameters covered by the two kits and what they are useful for:
| Water Quality Parameter | Why is this parameter important/interesting? | Water Rangers Freshwater Kit | YSI Probe |
| Temperature | Affects all other water quality parameters, species prefers certain temperature ranges | X | X |
| Conductivity | Presence of dissolved ions, like chloride | X | X |
| pH | Affects fish life or eggs, but varies based on type of substrate of water body | X | X |
| Alkalinity | Ability for water to neutralize acids | X | |
| Hardness | Measures presence of metals such as calcium and magnesium | X | |
| Total Dissolved Solids | Presence of minerals, salts, metals, cations, anions | X | |
| Secchi Depth | Water clarity or amount of suspended sediments | X | |
| Turbidity | Water clarity or amount of suspended sediments | X | |
| Oxidation Reduction Potential | Chemical reactions that are possible – oxidation reactions when positive, reduction reactions when negative | X | |
| Dissolved Oxygen | Fish need oxygen to live! This is temperature dependent. 4-7 mg/L needed for warm water fish, 7-11 mg/L needed for cold water fish | X | X |
In using both devices, the only real difficulty is with measuring dissolved oxygen. Water Rangers uses a Chemets kit for measuring dissolved oxygen. A small tube is broken underwater, then filled with sample water, and after two minutes the reaction creates a colour change. Then the sampler uses a guide to estimate the dissolved oxygen, to the nearest mg/L. Some photos below show examples of me figuring out what the right number is!
Now to the results of my test! I conducted six water quality tests where I used each kit at the exact same location. The Water Rangers kit got very similar results to the YSI probe. There was only one case where the data didn’t agree (Minto Creek, upstream) – but it was on a dissolved oxygen measurement and I think the issue was with the person doing the colour interpretation – aka me! The tables below show my results – but just for the parameters where there is a direct comparison.
Gull Lake, at water’s edge. August 12, 9:20am
| Water Quality Parameter | Water Rangers Kit | YSI Probe |
| Water Temperature (degrees Celsius) | 24.9 | 24.8 |
| Dissolved oxygen (mg/L) | 8 | 7.25 |
| Conductivity (uS/cm) | 61 | 66.3 |
| pH | 7.5 | 7.55 |
Minto Creek, downstream. August 12, 9:45am
| Water Quality Parameter | Water Rangers Kit | YSI Probe |
| Water Temperature (degrees Celsius) | 12.9 | 12.6 |
| Dissolved oxygen (mg/L) | 11 | 10.17 |
| Conductivity (uS/cm) | 70 | 51 |
| pH | 7.2 | 7.46 |
Minto Creek, upstream. August 12, 10:15am.
| Water Quality Parameter | Water Rangers Kit | YSI Probe |
| Water Temperature (degrees Celsius) | 15.7 | 15.4 |
| Dissolved oxygen (mg/L) | 11 | 7.71 |
| Conductivity (uS/cm) | 48 | 41.1 |
| pH | 7.2 | 7.09 |
Rackety Creek. August 12, 2:50pm.
| Water Quality Parameter | Water Rangers Kit | YSI Probe |
| Water Temperature (degrees Celsius) | 26.3 | 26.2 |
| Dissolved oxygen (mg/L) | 7 | 7.32 |
| Conductivity (uS/cm) | 40 | 43.0 |
| pH | 7.2 | 7.59 |
Gull Lake, at water’s edge. August 17, 10:30am.
| Water Quality Parameter | Water Rangers Kit | YSI Probe |
| Water Temperature (degrees Celsius) | 25.6 | 25.9 |
| Dissolved oxygen (mg/L) | 9 | 7.38 |
| Conductivity (uS/cm) | 61 | 66.8 |
| pH | 7.2 | 7.33 |
Gull Lake, middle of lake in a deep part. August 17, 2pm.
| Water Quality Parameter | Water Rangers Kit | YSI Probe |
| Water Temperature (degrees Celsius) | 25.9 | 26.1 |
| Dissolved oxygen (mg/L) | 8 | 7.70 |
| Conductivity (uS/cm) | 62 | 67.3 |
| pH | 7.8 | 7.79 |
Conclusion: I highly recommend the Water Rangers kit! It’s as good as having a probe worth thousands of dollars. It takes a little more work and some time getting used to doing the colour interpretation, but you can get the same results!
Check out more at www.waterrangers.ca, and see if there has been any water testing near you via the water rangers map: app.waterrangers.ca.