You may notice a trend recently, in that I am writing quite a bit about Neptune System’s products. While I’ve used an Apex controller for as long as I can remember, it’s only recently that I started to explore all of Fusion’s new enhancements, and began adding features onto my Apex. I’ve been impressed with what Neptune is building, a system that totally controls a reef aquarium and is easy to install. Also, firmware updates that were once painstaking can be accomplished easily, and new networking technologies make it possible to have a hardline network connection right at your tank. 

After installing the new neptune System’s WAV, I liked having detailed water circulation data so much, that I was hungry for more. One natural evolution of Fusion’s data center is PAR measurements. Many aquarists are not monitoring their PAR levels, and this is partially because in the past PAR monitors were expensive, and none were especially suited to continuous monitoring, which is most effective for reef aquariums. The first device to offer PAR monitoring was the Seneye aquarium monitor. While it was effective, the Seneye was difficult to place in an area within the tank, so getting accurate readings required holding it by hand in the exact position you wanted to measure. In short, its design failed to offer consistent PAR monitoring that was easily recorded and other half-baked features made it a less than ideal aquarium monitor.

neptune System’s PAR monitor takes an entirely different approach. The monitor is a small optical probe, and arrives with a piece of artificial live rock with a small hole that perfectly accepts and hides the sensor. After connecting a module with your apex (via an open aqua bus port) suddenly you have live PAR monitoring, along with a unit that is easy to place anywhere within your aquarium.

What is PAR?

PAR stands for photosynthetically active radiation and designates the wave band of solar radiation within a range of 400-700 nanometers that photosynthetic organisms require to fully photosynthesize. This tends to correspond with the range of light visible to the human eye. Shorter range photons can damage cells and tissue, but are naturally filtered out by the ozone layer and photons at longer ranges do not carry enough energy to allow for photosynthesis.

How does PAR help reef keepers:

As we all know, within photosynthetic coral tissues live zooxanthellae, which via photosynthesis pass extra nutrition over to our corals. It’s vitally important that photosynthesis is given a good opportunity to take place within our reef aquariums. Another point, various compounds within coral that create the colors we love react differently to various spectrums of light. In plants chlorophyll is the most abundant pigments, which captures red and blue light, but releases a characteristic green.

In corals, accessory pigments may utilize a certain light spectrum (or color) allowing them to give off a certain color effect. These can account for the reds, blues, orange and green colors that most reefers strive to enhance. It’s important to remember that zooxanthellae algae is drab brown or green in color, and that the striking displays we seek to create rely more on accessory pigments. PAR can aid reefers in determining if they are providing enough light to not only move photosynthesis along, but also cater to colorful accessory pigments.

How is PAR measured, and what measurements are reefers looking for?

PAR is measured in nano-meters, but exists as a measure of the energy within a spectrum of light, energy that can be used by algae within coral tissue to complete photosynthesis. It can also be a measure of energy for accessory pigments, allowing aquarists to tweak lighting to get different coloration results. A PAR reading is often represented with the following (uE m2 sec).

When measuring PAR, aquarists get a very definitive picture of how much active radiation is reaching their corals. Small polyp stony (SPS) corals require a lot of light, and often thrive in a PAR range of 300-600 (depending on species). Large polyp stony corals (LPS) can easily become damaged by high amounts of radiation, and thrive in PAR ranges of 70-200. For many LPS species, along with some SPS, exposure to PAR ranges in excess of 500, 600 causes tissue damage and eventually bleaching.

The goal of marine aquarists monitoring PAR is to find out what range is met within their aquarium. At the water’s surface and directly under lighting, PAR is often very high. On the tank bottom or at the edge of a light source’s coverage, it drops dramatically. If properly illuminated, aquarists find that there are a host of different PAR readings throughout their tank, and using that data greatly aids in the placement of various corals. It also shows you what the maximum light value of your tank is, along with the lowest light value, giving you a definitive idea of what species can be kept. Your tank may be too bright for some species, or not bright enough for others. For example Acropora digitifera is known to thrive in PAR values above 300 on up to 600. On the other hand some soft and LPS coral species are known to thrive in PAR values of 70 but no higher than 200. It’s going to be very tricky to set up a lighting system that provides for both species, but with a PAR meter’s aid, it’s possible.

Long term PAR monitoring:

PAR monitoring begins by measuring PAR throughout the tank. Using the neptune System’s meter, you can select choice areas where corals are placed, and simply move the meter to each and record their respective PAR measurements. Luckily apex Fusion records and graphs your PAR readings, so you have record of how PAR fluctuates within your tank. This is important data, as it gives you a high end reading, a low end reading and various readings in between the two.

At first, it lets you know what corals are properly placed for light penetration, what corals may be receiving too much light and species that aren’t getting enough. This aids aquarists in efficiently using their current lighting solution, as you may learn that more light hungry corals would fare within your tank, or find that your tank is capable of supporting a wide array of coral life.

Another important aspect of PAR monitoring is knowing how often PAR is available to your corals. You will notice, (if you use LED lights) that various ramp up stages produce no PAR. Yes, the corals may be bathed in blue light, but PAR remains at a constant 0. As the LED continues to ramp, PAR starts popping up at 10, 20, 30 and onwards and upwards. It’s valuable to know, with your current lighting schedule, for how many hours viable PAR is delivered to your corals. Most species need at least a solid 6 hours of PAR daily. You may find that if you’re running a light schedule for a total of 6 hours, of that only 4 or 4.5 provide PAR. If this is the case, you can adjust your light schedule as needed, so that for at least 6 hours PAR is delivered to your animals.

Once you’ve worked over the PAR values within your tank, I recommend setting the PAR meter somewhere that has the highest concentration of light. Once you’ve played with the readings, a good eyeball value of light should be possible. Having the highest reading and working down seems like a good approach to deciding on where to place new species. Another option is simply placing the PAR meter anywhere you intend to put a new specimen.

Installing the neptune System’s PAR monitor:

As I mentioned earlier, the Neptune System’s PAR kit comes with the actual PAR monitor, an Advanced Sensors Module (ASM) and a small piece of artificial rock, pre-fitted to accept the meter. It also includes an aqua bus (USB) cable. You will notice the PAR meter connects to the module with the same connector as a ph or ORP probe.

Installation is simple, and consists of connecting the ASM into an open aqua bus port on either your apex module or power bar. You then need to tell the apex, via the display and Setup menu that your ASM will be reading PARx7. Once that is done, the PAR meter is simply inserted into the artificial rock (which is actually REAL live rock, a man made live rock substitute) with the sensor facing up. Place the PAR meter and connect it to the ASM, and you’re done. You can also configure the apex display to show PAR readings on the home screen, right along with temperature, ph and ORP.

apex Fusion automatically adds the PAR console to your dashboard and begins recording and graphing PAR readings. It is advisable to keep the PAR meter clean of any dust, debris or algae. Obviously, if the sensor becomes encrusted or obstructed, it will affect the accuracy of your PAR reading.

Final Thoughts:

At $ 299 the neptune System’s PAR meter won’t be for everyone. It costs nearly as much as a decent protein skimmer. Considering high end PAR meters once sold for over $ 2,000, and this meter syncs with apex and keeps tallies of your readings, that price is certainly justifiable.

For any aquarist who wants hard data on how much usable energy lighting is providing their tank, then the PAR meter is an easy way to figure it out. As many of us know, using good data to make improvements to our aquariums often leads to exceptional results.