The Apogee Instruments Quantum Meter is an excellent reef tool. With so much of the focus in reefkeeping placed on lighting, one must wonder, how do I make sense of it all. A quantum meter is wonderfully helpful in measuring light intensity (specifically relevant to photosynthesis; we’ll get back to this), comparing bulbs and lighting options, making decisions about coral placement, and much more.
A quantum is simply the reference to the amount of energy carried by a photon. The Apogee Instrument Quantum meters approximate Photosynthetic Photon Flux (PPF) for Photo synthetically Active Radiation (PAR) between 400 and 700 nanometers. This is of value since photosynthetic organisms primarily utilize the number of photos between these wavelengths. PPF is measures as µmol m-2 s-1 (micromols of photos per meters squared per second).
Using a Quantum Meter
In order to use this meter in the aquarium, we mounted the sensor on a simple “holder” made of 3/4″ pvc ( a long piece, then an elbow, short connector piece, and another elbow). This allowed us to move the sensor around while always having it pointed at the light source. Once the sensor is mounted, we took several measurements above the waterline, then right below, and pretty much all over the tank.
Many hobbyists turn their powerheads/pumps off so that the water surface is not disturbed during the reading. We intentionally keep ours on, since that best replicates the conditions the corals are under. It was amazing to see how much variation there is within a pretty small area. We were able to compare metal halide reflectors, ballasts and bulbs, T5 reflectors, ballasts and bulbs (as well as the results of overdriving T5 bulbs). We will report specific results in follow-up articles.
Having used the quantum meter over a large number of display and frag tanks, and were extremely impressed with the information it provided.
Here is some information directly from Apogee Instruments
Apogee Instruments, developers of high-quality instrumentation to monitor the environment, is pleased to announce that our quantum meters now include both data recording capability and sun and electric calibration with each meter.
Each meter can store up to 99 manually recorded measurements. In automatic mode, measurements are made every 30 seconds and averages are stored every 30 minutes. Daily totals are also calculated and the past 99 days are recorded.
These meters still feature our innovative blue lens for improved spectral response along with our cosine-corrected head, self-cleaning characteristics, and long-term stability.