Portable oxygen and temperature meter complete with carry case and spares.
The most reliable and fool-proof oxygen meter on the market used by the most reputable fish farmers in the country. The oxyguard will quickly measure the dissolved oxygen and temperature of your water. Simple on/off button, check that the probe is reading within 1% of 100% and you're ready to test (quick and simple on-screen calibration if your handset isn't reading 100% saturation when dry). Not the cheapest oxygen meter on the market, but the best... and built to last!