Apogee DLI Quantum Meters Reviewed

Last Update: Mar 23, 2022

• Light Measurement

Apogee Instruments released their new line of quantum DLI meters consisting of the DLI-400, DLI-500, and DLI-600 to measure PPFD, DLI, and photoperiod. Check our review and our recommendation when and how to use them.

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Apogee Instruments, the renowned manufacturer of scientific-grade quantum PAR meters, recently released its new product line of daily light integral (DLI) meters. All three different DLI meters measure PAR as PPFD, DLI, and the photoperiod. The DLI meters are able to record and store the data for 99 days. Within this article, we want to take a look at these new products in the lens of a cannabis grower.

Contents

• A Quick Recap on the DLI
• Instantaneous DLI vs. Integrating DLI
• Who’s It For
• Apogee DLI Meter Product Line
• Alternatives
• PAR Meter + Calculation Photone Grow Light Meter App

A Quick Recap on the DLI

The daily light integral (DLI) is the total sum of photosynthetic lighting intensity measured as PPFD over a 24 hour period. Ultimately, supplying an adequate amount of light is the single most important factor when it comes to plant lighting. If want to know more about DLI, we recommend reading our articles about the DLI in general or specific for the cannabis plant.

Instantaneous DLI vs. Integrating DLI

Taking a DLI measurement therefore requires measuring PPFD using an accurate PAR meter and knowing how long this PPFD is supplied to the plants. Hence, every DLI meter is taking real-time PPFD measurements that are then summed up to cover the entire 24 hour window. However, there are two fundamental differences in how long and how often those measurements are taken: An integrating DLI meter is taking measurements every few minutes throughout the day and calculating the sum of them. As a result, the actual DLI measurement is only available after the full 24 hour period.

An instantaneous DLI meter however, allows to measure once and then multiplies the spot PPFD measurement with a configured photoperiod (i.e. the amount of time the plants are exposed to the light) in order to obtain the DLI measurement instantly.

Who’s It For

If you’re using artificial lighting, you already know the photoperiod as you are controlling the lighting duration yourself. Thus, it’s way easier and quicker to take instantaneous DLI measurements with manual entries of the photoperiod according to your light schedule. In this case, you don’t need an integrating DLI meter such as those from Apogee and you will be better off using the DLI feature of our Grow Light Meter app.

📷Natural sunlight's PPFD is changing throughout the day whereas grow light PPFD stays the same as long as the lights are on

If, however, natural lighting comes into play, using an integrating DLI meter from Apogee may result in better lighting decisions. If you’re running a greenhouse with supplemental grow lighting, knowing the amount of light your plants receive is crucial for an economical operation. In such cases, using a multi-day measurement is the best option to optimize your grow light schedule across the season.

📷A large-scale cannabis grow using supplemental HID grow lights. If your grow looks like this, you should probably get an integrating DLI meter.

Apogee DLI Meter Product Line

Apogee offers a product line of three different DLI meters covering different measurement aspects.

📷All three Apogee DLI meters: The DLI-400, DLI-500, and DLI-600. Image taken from Apogee's website.

The user interface and software capabilities are the same on all three meters. The main difference is the accuracy and spectral sensitivity of PPFD measurements, which is also represented in the prices ranging from $300 to $550 as of February 2022.

The DLI-400 has the lowest-cost PAR sensor that is not representing the 400 to 700 nm PAR spectrum accurately for all light sources. It is therefore only recommended to measure natural sunlight.

The DLI-500 offers the same accuracy and spectral response as Apogee’s full-spectrum quantum sensors and can be used for any type of grow light – be it the sun, HPS, LED, MH, CMH, or anything else.

The DLI-600 is extending the 400 to 700 nm PAR spectrum into the infrared spectrum to provide an extended ePAR PPFD measurement. It can be used for any type of grow light as well.

Alternatives

If you’re running your grow entirely on artificial lighting using high-powered grow lights, you don’t need an integrating DLI meter. What you’d need is an accurate and trustworthy PAR meter to measure the PPFD your plants receive.

You mainly have two options: Using a dedicated PAR meter and calculating the DLI yourself using the formula below, or using our grow light meter app that measures PPFD and already does the DLI calculation for you.

PAR Meter + Calculation

PAR meters are available from different manufacturers with the most renowned being Apogee and its MQ-500 full-spectrum quantum meter. There are other alternatives such as the Licor LI-190R quantum sensor or the SpotOn® quantum PAR light meter. All of them are of high quality, accurate, and trustworthy. Another thing they have in common is their hefty price tag upwards of $300 to $500 which makes them hard to obtain for enthusiasts and professionals alike.

If you’re using a PAR meter, your measurement is a spot PPFD measurement, meaning that you’re measuring the levels of PAR within this spot and right now. In order to obtain the DLI, the spot PPFD measurement must be multiplied with the time your grow lights are kept on (i.e. the photoperiod). The formula is rather simple and as follows:

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DLI = PPFD x Photoperiod x (3600 / 1000000)

Fortunately enough, there are online calculators available. This one gives you all the options you need.

Photone Grow Light Meter App

There is an easier, more accessible, and way cheaper option to measure DLI than using a traditional PAR meter: Our Photone Grow Light Meter app. The app allows you to take accurate PPFD measurements as well as measuring DLI directly with the lighting duration (or photoperiod respectively) set by you based on your grow lights' schedule.

Download📷If you haven’t used our app yet, we definitely recommend giving it a try! Photone is free to download on iOS and Android and may even save you hundreds of dollars otherwise unnecessarily spent on physical meters.

Thank you for reading and happy growing!

Sources

• The title image is taken from Apogee Instruments, Inc.'s website.

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• 📷Full DescriptionDLI-500: PAR, Daily Light Integral, and Photoperiod Meter (Full-Spectrum, 400-700 nm) $495.00DLI-500 FULL-SPECTRUM METER - New for 2022, the Apogee Instruments' DLI-500 is an elegant, simple-to-use device for spot checking photosynthetically active radiation (PAR; 400-700 nm) levels and measuring...

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Description Specifications Share DLI-500 FULL-SPECTRUM METER - New for 2022, the Apogee Instruments' DLI-500 is an elegant, simple-to-use device for spot checking photosynthetically active radiation (PAR; 400-700 nm) levels and measuring daily light integral (DLI) and photoperiod under all light sources. DLI refers to the total amount of PAR or extended PAR (ePAR) incident on a plane in a 24-hour period, expressed in units of moles per square meter per day (mol m-2 d-1). Photoperiod is the total amount of time in which PAR or ePAR is incident on a plane during a 24-hour period and is expressed in units of hours (h). PAR, DLI, and photoperiod influence plant growth and development, and they are often measured in greenhouses and growth chambers to aid in light management and decision making. The DLI-500 is accurate under all light sources, but if you are looking for a low-cost option accurate under sunlight and some broadband light sources only, see our DLI-400 model.APOGEE QUALITY - Our products are developed for use by the Apogee Instruments’ engineering team under the direction of world-renowned crop physiologist, Dr. Bruce Bugbee, and are considered the gold-standard by agricultural professionals and researchers for measuring PAR levels for growing plants. The DLI-500 features the same ultra-accurate 400-700 nm full-spectrum photodetector as our famous MQ-500 meter, with even more features and functionality, but it lacks a two meter cable.ACCURATE, STABLE MEASUREMENTS - Our research-grade sensors are trusted by scientists and serious growers all over the world for their accuracy and stability. Hobby-grade meters are often accurate out of the box, but drift in accuracy quickly. However, Apogee research-grade quantum sensors have an industry-leading accuracy drift rate of less than 2 % per year. All sensors are NIST traceable and are built and calibrated at our headquarters in Logan, Utah, USA.MEASUREMENT MODES - This rugged, water resistant, and compact meter is perfect for single (spot checking areas) or continuous measurements of PPFD or ePPFD; DLI; and photoperiod. The DLI-500 meter has two different screen modes to display the measurements: stored data and live view data. In the stored data screen, it shows the DLI measurement, photoperiod, and which day the data was collected (up to 99 days ago). The live view data screen displays a running average of PPFD from the last 2.5 seconds. Measuring and controlling the DLI and the hours of light a plant receives (photoperiod) is critical for optimizing plant health, triggering flowering, and inducing other plant morphology effects. PPFD, DLI, and photoperiod data can be viewed onscreen or downloaded via USB-C cable for analysis.RUGGED & READY TO USE - Built tough and rated IP65 to withstand harsh and humid environments, the DLI-500 can be carried around for spot checking, placed directly on any level surface, or mounted by attaching to commonly available camera tripods, clamps, or stakes using the standard ¼-20 threaded port on the bottom. The DLI meters consist of a cast acrylic diffuser (filter), optical filter, photodiode, signal processing circuitry, and an LCD display mounted in an ASA plastic housing. Each DLI package includes the meter, a protective carrying case, two AAA batteries, a quickstart instruction guide, a screwdriver, a soil spike for easy mounting, and a USB-C cable for downloading the meter's stored data as a CSV file to a computer.MADE IN THE USA - All meters are designed, built, and calibrated at our headquarters in Logan, Utah, USA. Apogee Instruments has been creating research-grade instruments for scientists and serious growers for over 25 years. All meters are backed by our industry leading four-year warranty and supported by our world-class, US-based customer support team.FOR MORE PRODUCT INFORMATION, CHECK OUT THESE LINKS• Product Manual• Specification Sheet• Technical Drawing

Related Products 📷 Quick View MQ-500: Full-Spectrum Quantum Meter $532.00 📷 Quick View DLI-400: PAR, Daily Light Integral, and Photoperiod Meter (Sunlight Only, 400-700 nm) $298.00 📷 Quick View DLI-600: ePAR, Daily Light Integral, and Photoperiod Meter (ePAR, 400-750 nm) $525.00

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