{"id":3113,"date":"2015-04-17T22:56:48","date_gmt":"2015-04-18T05:56:48","guid":{"rendered":""},"modified":"2025-07-18T10:57:17","modified_gmt":"2025-07-18T17:57:17","slug":"3113","status":"publish","type":"post","link":"https:\/\/www.vernier.com\/til\/3113","title":{"rendered":"PAR Troubleshooting and FAQs"},"content":{"rendered":"<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-9d6595d7 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\">\n<div style=\"height:40px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n<h3 class=\"wp-block-heading\"><a href=\"\/product\/par-sensor\/\">PAR Sensor<\/a> (<nobr>PAR-BTA<\/nobr>)<\/h3>\n<div style=\"height:20px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n<p><a href=\"\/manuals\/PAR-BTA\">Specifications and User Guide<\/a><\/p>\n<\/div>\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\">\n<figure class=\"wp-block-image size-large\"><img decoding=\"async\" src=\"https:\/\/www.vernier.com\/wp-content\/uploads\/2019\/11\/product.updated.par-bta.hero._001.jpg\" alt=\"\"\/><\/figure>\n<\/div>\n<\/div>\n<p class=\"has-very-light-gray-background-color has-background\"><strong><a href=\"\/til\/17324\/\">Which Apogee sensor head does my PAR Sensor have?<\/a><\/strong><br \/>In May of 2023 the SQ-100X sensor head was introduced for the PAR sensor (previous model was SQ-110). <span style=\"font-weight: 400;\">The head of the new sensor is attached to the main cable using a P68-rated stainless-steel marine grade (M8) connector. This connector is located 25 cm from the sensor head.<\/span> The sensor model number can be found on a white label wrapped around the cable that is located a few centimeters from the sensor head (SQ-100X-SS or SQ-110). The new sensor has a default calibration for solar radiation (outside light) and electric light sources.<\/p>\n<div style=\"height:10px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n<h3 class=\"wp-block-heading\">Troubleshooting<\/h3>\n<ul class=\"wp-block-list\">\n<li><strong>Primary Test:<\/strong> Make sure that the sensor detects sunlight. Values for a bright sunny summer day should approach 2000 \u00b5mol m\u203e\u00b2s\u203e\u00b9 of photosynthetic photon flux.<\/li>\n<li><strong>Secondary Test:<\/strong> If indoors, you can use an electric lamp that should produce a PAR reading greater than 10 \u00b5mol m\u203e\u00b2s\u203e\u00b9. Place the sensor head approximately 10 cm away from a lit lamp source where values should be greater than the residual background value. When the PAR Sensor is used with some artificial lighting, the lamp flicker may cause a fluctuating signal.<\/li>\n<\/ul>\n<p>To accurately measure light from an artificial source that uses LEDs, a correction factor must be used. See <a href=\"\/til\/3102\/\">Can I use Vernier PAR sensors with electric lights? When do I need to use a Correction Factor?<\/a><\/p>\n<div style=\"height:20px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n<h3 class=\"wp-block-heading\">Additional Troubleshooting<\/h3>\n<ul class=\"wp-block-list\">\n<li><a href=\"\/til\/3105\/\">How do Vernier PAR sensors work?<\/a><\/li>\n<li><a href=\"\/til\/3104\/\">How is Photosynthetically Active Radiation (PAR) Measured?<\/a><\/li>\n<li><a href=\"\/til\/3099\/\">Do I need to calibrate Vernier PAR sensors?<\/a><\/li>\n<li><a href=\"\/til\/3107\/\">How are Vernier PAR sensors calibrated?<\/a><\/li>\n<li><a href=\"\/til\/3108\/\">Can I calibrate my PAR Sensor using the clear sky calculator<\/a><\/li>\n<li><a href=\"\/til\/3103\/\">How do I clean a PAR Sensor?<\/a><\/li>\n<li><a href=\"\/til\/17520\/\">How do I apply a Correction Factor to Vernier PAR sensors?<\/a><\/li>\n<li><a href=\"\/til\/1948\/\">Can I use a Vernier light sensors to measure PAR?<\/a><\/li>\n<li><a href=\"\/til\/3106\/\">Are Vernier PAR sensors waterproof?<\/a><\/li>\n<\/ul>\n<div style=\"height:20px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n<h3 class=\"wp-block-heading\">Specifications<\/h3>\n<ul class=\"wp-block-list\">\n<li>Sensing Element<br \/>\u26ac Current: SQ-100x series quantum sensor (calibrated for sunlight and electric light sources)<br \/>\u26ac Pre-May 2023: SQ-110 sensor (calibrated for sunlight)<\/li>\n<li>PAR Range: 0 to 2500 \u03bcmol m<sup>-2<\/sup> s<sup>-1<\/sup> (PPFD) in full sun<\/li>\n<li>Absolute Accuracy: \u00b15%<\/li>\n<li>Repeatability: \u00b11%<\/li>\n<li>Long-Term Drift: Less than 2% per year<\/li>\n<li>Cosine Response:<br \/>\u26ac 45\u00b0 zenith angle: \u00b12%<br \/>\u26ac 75\u00b0 zenith angle: \u00b15%<\/li>\n<li>Wavelength range: 370 nm to 650 nm<\/li>\n<li>Typical Resolution: 1 \u03bcmol m<sup>-2<\/sup> s<sup>-1<\/sup> (PPFD)<\/li>\n<li>Sensor dimensions<br \/>\u26ac Diameter: 2.4 cm<br \/>\u26ac Height: 3.3 cm<br \/>\u26ac Cable length: 5 m<\/li>\n<li>Materials: Anodized aluminum with case acrylic lens<\/li>\n<li>Operating Environment<br \/>\u26ac Sensor Head and Cable<br \/>\u2003\u25b8 \u201310 to 60 \u00b0C<br \/>\u2003\u25b80 to 100% relative humidity<br \/>\u2003\u25b8Sensor head and cable can be submerged in water to the level of the sensor box.<br \/>\u26ac Sensor Box<br \/>\u2003\u25b80 to 40 \u00b0C<br \/>\u2003\u25b8Sensor box is not waterproof or weatherproof.<\/li>\n<li>Default calibration coefficients: slope = 500 \u00b5mol m\u203e\u00b2s\u203e\u00b9\/ Volt; intercept = 0<\/li>\n<\/ul>\n<div style=\"height:20px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n<h3 class=\"wp-block-heading\">Calibration<\/h3>\n<p>Calibrate? No. The sensor is set to the stored calibration before shipping. If you are suspicious about the calibration, there are two ways to check.<\/p>\n<ol class=\"wp-block-list\">\n<li>Compare the PAR value with another Quantum sensor.<\/li>\n<li>Use the Clear Sky Calibration method. You will need a sunny day with no clouds or pollution effects.\n<ol style=\"list-style-type:lower-alpha\" class=\"wp-block-list\">\n<li>Access the <a href=\"http:\/\/www.clearskycalculator.com\">Clear Sky website<\/a> where you can enter data into the web application to have the photosynthetic photon flux (PPF) calculated. <\/li>\n<li>Input values for the calculation including latitude, longitude, altitude, time of day, day of year, air temperature, and relative humidity. <\/li>\n<li>You can compare the calculated value with the reading on the PAR Sensor. <\/li>\n<li>This procedure should be done at several different times. If the readings are consistently off, contact Vernier.<\/li>\n<\/ol>\n<\/li>\n<\/ol>\n<p><strong>Note: <\/strong>Debris build-up on the lens of the PAR Sensor is a common cause of inaccurate readings.<\/p>\n<div style=\"height:20px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n<h3 class=\"wp-block-heading\">Additional Products<\/h3>\n<p>Here are some additional products appropriate for experiments involving photosynthesis of plants, algae, and other photoautotrophs under terrestrial and aquatic conditions.<\/p>\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-9d6595d7 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\">\n<h4 class=\"wp-block-heading\"><strong>LABQUEST (WIRED) SENSORS<\/strong><\/h4>\n<ul class=\"wp-block-list\">\n<li><a href=\"\/product\/vernier-optical-do-probe\/\">Vernier Optical DO Probe<\/a> (<nobr>ODO-BTA<\/nobr>)<\/li>\n<li><a href=\"\/product\/co2-gas-sensor\/\">CO<sub>2<\/sub> Gas Sensor<\/a> (<nobr>CO2-BTA<\/nobr>)<\/li>\n<li><a href=\"\/product\/o2-gas-sensor\/\">O<sub>2<\/sub> Gas Sensor<\/a> (<nobr>O2-BTA<\/nobr>)<\/li>\n<li><a href=\"\/product\/extra-long-temperature-probe\/\">Extra-Long Temperature Probe<\/a> (<nobr>TPL-BTA<\/nobr>)<\/li>\n<li><a href=\"\/product\/ph-sensor\/\">pH Sensor<\/a> (<nobr>PH-BTA<\/nobr>)<\/li>\n<li><a href=\"\/product\/tris-compatible-flat-ph-sensor\/\">Tris-Compatible Flat pH Sensor<\/a> (<nobr>FPH-BTA<\/nobr>)<\/li>\n<li><a href=\"\/product\/conductivity-probe\/\">Conductivity Probe<\/a> (<nobr>CON-BTA<\/nobr>)<\/li>\n<li><a href=\"\/product\/salinity-sensor\/\">Salinity Sensor<\/a> (<nobr>SAL-BTA<\/nobr>)<\/li>\n<li><a href=\"\/product\/water-quality-bottles-8-bottles\/\">Water Quality Bottles (8 bottles)<\/a> (<nobr>WQ-BOT<\/nobr>)<\/li>\n<\/ul>\n<\/div>\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\">\n<h4 class=\"wp-block-heading\"><strong>GO DIRECT SENSORS<\/strong><\/h4>\n<ul class=\"wp-block-list\">\n<li><a href=\"\/product\/go-direct-par-photosynthetically-active-radiation\/\">Go Direct<sup>&reg;<\/sup>  PAR (Photosynthetically Active Radiation)<\/a> (<nobr>GDX-PAR<\/nobr>)<\/li>\n<li><a href=\"\/product\/go-direct-optical-dissolved-oxygen-probe\/\">Go Direct<sup>&reg;<\/sup> Optical Dissolved Oxygen Probe<\/a> (<nobr>GDX-ODO<\/nobr>)<\/li>\n<li><a href=\"\/product\/go-direct-co2-gas-sensor\/\">Go Direct<sup>&reg;<\/sup> CO<sub>2<\/sub> Gas Sensor<\/a> (<nobr>GDX-CO2<\/nobr>)<\/li>\n<li><a href=\"\/product\/go-direct-o2-gas-sensor\/\">Go Direct<sup>&reg;<\/sup> O<sub>2<\/sub> Gas Sensor<\/a> (<nobr>GDX-O2<\/nobr>)<\/li>\n<li><a href=\"\/product\/go-direct-ph-sensor\/\">Go Direct<sup>&reg;<\/sup> pH Sensor<\/a> (<nobr>GDX-PH<\/nobr>)<\/li>\n<li><a href=\"\/product\/go-direct-tris-compatible-flat-ph\/\">Go Direct<sup>&reg;<\/sup> Tris-Compatible Flat pH<\/a> (<nobr>GDX-FPH<\/nobr>)<\/li>\n<li><a href=\"\/product\/go-direct-conductivity-probe\/\">Go Direct<sup>&reg;<\/sup> Conductivity Probe<\/a> (<nobr>GDX-CON<\/nobr>)<\/li>\n<li><a href=\"\/product\/go-direct-salinity-sensor\/\">Go Direct<sup>&reg;<\/sup> Salinity Sensor<\/a> (<nobr>GDX-SAL<\/nobr>)<\/li>\n<li><a href=\"\/product\/water-quality-bottles-8-bottles\/\">Water Quality Bottles (8 bottles)<\/a> (<nobr>WQ-BOT<\/nobr>)<\/li>\n<\/ul>\n<\/div>\n<\/div>","protected":false},"excerpt":{"rendered":"<p>Specifications and User Guide In May of 2023 the SQ-100X sensor head was introduced for the PAR sensor (previous model was SQ-110). The head of&#8230;<\/p>\n","protected":false},"author":1073,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[],"tags":[720,1487,5220,5221,5216,5215,5222],"class_list":["post-3113","post","type-post","status-publish","format-standard","hentry","tag-maintil","tag-par","tag-par-bta-par-bta","tag-parmain","tag-ppf","tag-ppfd","tag-vernier-par-sensor"],"acf":[],"_links":{"self":[{"href":"https:\/\/www.vernier.com\/til\/wp-json\/wp\/v2\/posts\/3113","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.vernier.com\/til\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.vernier.com\/til\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.vernier.com\/til\/wp-json\/wp\/v2\/users\/1073"}],"replies":[{"embeddable":true,"href":"https:\/\/www.vernier.com\/til\/wp-json\/wp\/v2\/comments?post=3113"}],"version-history":[{"count":0,"href":"https:\/\/www.vernier.com\/til\/wp-json\/wp\/v2\/posts\/3113\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.vernier.com\/til\/wp-json\/wp\/v2\/media?parent=3113"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.vernier.com\/til\/wp-json\/wp\/v2\/categories?post=3113"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.vernier.com\/til\/wp-json\/wp\/v2\/tags?post=3113"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}