{"product_id":"bluelab-onepen-replacement-probe","title":"Bluelab OnePen Replacement Probe – pH, EC \u0026 Temp Sensor","description":"\u003ch2\u003eA fresh sensor that keeps your OnePen reading true\u003c\/h2\u003e\u003cp\u003eThe \u003cstrong\u003eBluelab OnePen Replacement Probe\u003c\/strong\u003e is the genuine spare sensor for the \u003cstrong\u003eBluelab OnePen\u003c\/strong\u003e, the 3-in-1 meter that reads \u003cstrong\u003epH, conductivity (EC) and temperature\u003c\/strong\u003e from a single dip. Everything that wears lives in the probe: a \u003cstrong\u003edouble-junction pH probe\u003c\/strong\u003e, \u003cstrong\u003etitanium EC electrodes\u003c\/strong\u003e and the temperature sensor, in an \u003cstrong\u003eIP68\u003c\/strong\u003e waterproof and dustproof body. When it ages you change this part and keep the pen, its display and its Bluetooth link to the Edenic app.\u003c\/p\u003e\u003ch3\u003eKey Benefits\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eAll three readings restored\u003c\/strong\u003e – pH, EC and temperature in one swap\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eGenuine Bluelab part\u003c\/strong\u003e – the OnePen flags an incorrect probe, so only an official probe will do\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDouble-junction pH probe\u003c\/strong\u003e with \u003cstrong\u003e0.01 pH\u003c\/strong\u003e resolution and \u003cstrong\u003e±0.05 pH\u003c\/strong\u003e accuracy at 25 °C\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTitanium EC electrodes\u003c\/strong\u003e resist corrosion and read 0–10.0 EC\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eIP68 rated\u003c\/strong\u003e once fitted – safe at the reservoir edge\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eQuick to fit\u003c\/strong\u003e – an alignment arrow and threaded collar, no tools\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eWhen Should the Probe Be Replaced?\u003c\/h3\u003e\u003cp\u003eBluelab put the average life of a OnePen probe at about \u003cstrong\u003e18 months\u003c\/strong\u003e, depending on how well it is cleaned and stored. The signs are a pH reading that will not calibrate, drifts or settles slowly after a proper clean and a 24-hour KCl soak, or an EC reading that no longer matches 2.77 EC standard solution. A meter that reads wrong leads to wrong corrections: pH out of range costs \u003cstrong\u003enutrient uptake\u003c\/strong\u003e, and an EC that reads low ends in overfeeding and tip burn.\u003c\/p\u003e\u003ch3\u003eHow to Use\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eRemove\u003c\/strong\u003e the storage cap and hold the pen upside down so the batteries stay in place.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUnscrew\u003c\/strong\u003e the threaded collar and pull the old probe straight out of the pen body.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFit\u003c\/strong\u003e the new probe with its protective cap removed, lining the arrow up with the notch, and push it fully home.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTighten\u003c\/strong\u003e the threaded collar fully to restore the waterproof seal.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCalibrate\u003c\/strong\u003e pH at 7.0 then 4.0, and check EC in 2.77 EC standard solution.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eStore\u003c\/strong\u003e with a few drops of KCl storage solution on the sponge in the cap; never soak the EC electrodes in KCl and never use RO, distilled or deionised water.\u003c\/li\u003e\n\u003c\/ul\u003e\u003cdiv class=\"hcs-specs\"\u003e\n\u003ch3\u003eTechnical Specifications\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eFits:\u003c\/strong\u003e Bluelab OnePen only\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSensors:\u003c\/strong\u003e double-junction pH probe, titanium conductivity electrodes, temperature sensor\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003epH:\u003c\/strong\u003e 0.0–14.0, resolution 0.01, accuracy ±0.05 at 25 °C\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eConductivity:\u003c\/strong\u003e 0–10.0 EC or mS\/cm (resolution 0.01, accuracy ±0.1), 0–100 CF, 0–5000 ppm (500 scale), 0–7000 ppm (700 scale)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTemperature:\u003c\/strong\u003e 0–50 °C \/ 32–122 °F, accuracy ±1\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCalibration:\u003c\/strong\u003e pH two-point (7.0 and 4.0, or 7.0 and 10.0); EC factory calibrated, checked against 2.77 EC solution\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRating:\u003c\/strong\u003e IP68 water and dust ingress\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAverage life:\u003c\/strong\u003e about 18 months with correct care (Bluelab)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWarranty:\u003c\/strong\u003e 6 months\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBluelab part code:\u003c\/strong\u003e PROBONE\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/div\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cdiv class=\"hcs-faq\"\u003e\n\u003cdetails style=\"border:1px solid #e6e6e6;border-radius:8px;padding:12px 16px;margin:0 0 8px;\"\u003e\u003csummary style=\"cursor:pointer;font-weight:600;\"\u003eWill it fit the pH PenPlus or another Bluelab pen?\u003c\/summary\u003e\u003cp style=\"margin:10px 0 0;\"\u003eNo. It fits the Bluelab OnePen only. The pH PenPlus takes the Bluelab pH ProbePlus, and the standard pH Pen and Conductivity Pen have sealed probes.\u003c\/p\u003e\u003c\/details\u003e\u003cdetails style=\"border:1px solid #e6e6e6;border-radius:8px;padding:12px 16px;margin:0 0 8px;\"\u003e\u003csummary style=\"cursor:pointer;font-weight:600;\"\u003eDo I need to recalibrate after fitting it?\u003c\/summary\u003e\u003cp style=\"margin:10px 0 0;\"\u003eYes. Calibrate pH at 7.0 then 4.0 before the first reading, and check the EC reading in 2.77 EC standard solution.\u003c\/p\u003e\u003c\/details\u003e\u003cdetails style=\"border:1px solid #e6e6e6;border-radius:8px;padding:12px 16px;margin:0 0 8px;\"\u003e\u003csummary style=\"cursor:pointer;font-weight:600;\"\u003eHow long will the new probe last?\u003c\/summary\u003e\u003cp style=\"margin:10px 0 0;\"\u003eBluelab quote an average of about 18 months. Cleaning it regularly and keeping the pH bulb wet with KCl storage solution are what make the difference.\u003c\/p\u003e\u003c\/details\u003e\n\u003c\/div\u003e\u003ch3\u003eWorks Well With\u003c\/h3\u003e\u003cdiv class=\"hcs-related\" style=\"display:flex;flex-wrap:wrap;gap:10px;margin:12px 0 0;\"\u003e\n\u003ca href=\"\/products\/bluelab-ph-7-0-solution-sachets\" style=\"flex:1 1 240px;display:flex;align-items:center;gap:12px;padding:10px 12px;border:1px solid #e6e6e6;border-radius:8px;text-decoration:none;color:inherit;background:#fff;\"\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0748\/7127\/5786\/files\/bluelab-ph-7-0-solution-sachets-1.png?v=1790169276\u0026amp;width=160\" alt=\"Bluelab pH 7.0 Solution Sachets\" width=\"64\" height=\"64\" loading=\"lazy\" style=\"width:64px;height:64px;object-fit:contain;flex:none;\"\u003e\u003cspan style=\"font-size:14px;line-height:1.4;\"\u003e\u003cstrong style=\"display:block;\"\u003eBluelab pH 7.0 Solution Sachets\u003c\/strong\u003e\u003cspan style=\"color:#008d37;\"\u003eFirst pH calibration point\u003c\/span\u003e\u003c\/span\u003e\u003c\/a\u003e\u003ca href=\"\/products\/bluelab-ph-4-0-solution-sachets\" style=\"flex:1 1 240px;display:flex;align-items:center;gap:12px;padding:10px 12px;border:1px solid #e6e6e6;border-radius:8px;text-decoration:none;color:inherit;background:#fff;\"\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0748\/7127\/5786\/files\/bluelab-ph-4-0-solution-sachets-default-title-1.png?v=1790169273\u0026amp;width=160\" alt=\"Bluelab pH 4.0 Solution Sachets\" width=\"64\" height=\"64\" loading=\"lazy\" style=\"width:64px;height:64px;object-fit:contain;flex:none;\"\u003e\u003cspan style=\"font-size:14px;line-height:1.4;\"\u003e\u003cstrong style=\"display:block;\"\u003eBluelab pH 4.0 Solution Sachets\u003c\/strong\u003e\u003cspan style=\"color:#008d37;\"\u003eSecond pH calibration point\u003c\/span\u003e\u003c\/span\u003e\u003c\/a\u003e\u003ca href=\"\/products\/bluelab-ec-277-solution-sachets\" style=\"flex:1 1 240px;display:flex;align-items:center;gap:12px;padding:10px 12px;border:1px solid #e6e6e6;border-radius:8px;text-decoration:none;color:inherit;background:#fff;\"\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0748\/7127\/5786\/files\/bluelab-ec-277-solution-sachets-1.png?v=1790169268\u0026amp;width=160\" alt=\"Bluelab 2.77 EC Solution Sachets\" width=\"64\" height=\"64\" loading=\"lazy\" style=\"width:64px;height:64px;object-fit:contain;flex:none;\"\u003e\u003cspan style=\"font-size:14px;line-height:1.4;\"\u003e\u003cstrong style=\"display:block;\"\u003eBluelab 2.77 EC Solution Sachets\u003c\/strong\u003e\u003cspan style=\"color:#008d37;\"\u003eChecks the EC reading after fitting\u003c\/span\u003e\u003c\/span\u003e\u003c\/a\u003e\u003ca href=\"\/products\/kcl-ph-probe-storage-solution\" style=\"flex:1 1 240px;display:flex;align-items:center;gap:12px;padding:10px 12px;border:1px solid #e6e6e6;border-radius:8px;text-decoration:none;color:inherit;background:#fff;\"\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0748\/7127\/5786\/files\/kcl-ph-probe-storage-solution.jpg?v=1787262443\u0026amp;width=160\" alt=\"Growth Technology KCL Storage Solution\" width=\"64\" height=\"64\" loading=\"lazy\" style=\"width:64px;height:64px;object-fit:contain;flex:none;\"\u003e\u003cspan style=\"font-size:14px;line-height:1.4;\"\u003e\u003cstrong style=\"display:block;\"\u003eGrowth Technology KCL Storage Solution\u003c\/strong\u003e\u003cspan style=\"color:#008d37;\"\u003eKeeps the pH bulb hydrated\u003c\/span\u003e\u003c\/span\u003e\u003c\/a\u003e\n\u003c\/div\u003e","brand":"Bluelab","offers":[{"title":"Default Title","offer_id":53929890349322,"sku":"TLS-BLUE-018-01","price":92.9,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0748\/7127\/5786\/files\/bluelab-onepen-replacement-probe-default-title-1.jpg?v=1792261673","url":"https:\/\/hydrocropshop.co.uk\/products\/bluelab-onepen-replacement-probe","provider":"Hydro Crop Shop","version":"1.0","type":"link"}