Review: Kessil AP700 light fixture

While writing for reefs.com I infamously criticized the price of the Kessil AP700 light fixture. I compared its cost to other popular fixtures and noted that they were at least $ 200 more than competitors. Anyone who read that would likely be surprised that for several months now, my primary reef tank (a 250 gallon) has been lit by the Kessil AP700, three of them to be exact. What made me forgo my good judgement and plunk down almost $ 3,000 on Kessil’s new, and albeit pricey lights?

Before upgrading to a custom designed reef tank, I had used Kessil’s A360 line of lights over my reef. Like other reef keepers, I was impressed, not only with their simplicity but also the quality of light. It was reminiscent of the bright, shimmering light produced by metal halides. It wasn’t flat and devoid of life, like common LED output. Under Kessil’s lighting, I experienced great growth and impressive polyp extension. When I upgraded to my new tank, mounting A360’s over it was nearly impossible. I made the switch to another light and after almost two-years, was never fully pleased with the result.

The hunt began for a new light fixture. I discounted the AP700 almost immediately, due to cost. However, when I started looking at other high-end reef lighting options, the cost didn’t seem so bad. The Orphek Atlantik, a light I closely investigated was $ 1,200 per fixture. Even though it was larger than the AP700, I would still need three to light my tank. That’s a total of $ 3,600 bucks for lighting. Other lights I investigated were nearly the same price and based on this, the Kessil AP700 was actually a value. I started to wonder how my old lights contained so much control technology, but were sold for less than other options.

I decided to give the Kessil AP700’s a shot. While there are a few issues I feel reef keepers should be aware of, overall the quality of light they produce and coral growth under them has been more than sufficient. Many of the shortcomings experienced with the Kessil AP700 are present in any single point light source and careful planning and set-up can work around those problems.

The saga of single point lighting:

LED lighting that uses light pucks, or clusters of diodes can all be considered single point light sources. These are spotlight style lights, that produce a very powerful spectrum at the center of the light, then diffuse that light throughout the tank as it wanes, further from the source of light. While it’s popular for reef tanks, this design isn’t without a host of draw backs. One, it’s prone to shadowing, meaning areas of the tank are void of usable light, simple because of how the light diffuses downward. Any water ripple or fish movement can break up the light and leave spots within the tank shadowed, potentially for long periods of time. Many argue that in the wild, corals are often shadowed by cloud cover or storms. This is true, however the power of the tropical sun is well beyond our capabilities to reproduce with hobby grade lights, meaning that what our corals get within our tanks, pales in comparison to what they get in the wild.

Because of issues with single-point (spotlight) style lights, aquarists often encounter issues with coral growth. Corals grow to about the size of a fist (give or take) and then growth tapers off. The coral has simply outgrown the useable light within the tank, and part of the colony now extends beyond where the spotlight provides ample photosynthetic radiation. If your goal is a tank-full of fist sized corals grown from frags, this may not be a problem. However, if your goal is constant extensive growth, then you’re bound to encounter an issue. Often aquarists with single point light sources will buy a large coral colony, several inches in size, only to be suddenly dismayed when the colony starts to die off around the edges. It’s important to understand that all LED diodes (the individual diodes) are a pinpoint light source. This means that they create light in one-direction and have limited spread. The chipset within an LED fixture is there to ensure each diode is mimicking and balancing color, so that the aquarist doesn’t get color spots (areas where diode color is different and can be noticed while viewing the aquarium). These advanced chipsets are present to do what other light sources do inherently, create a uniform and even color throughout the tank.

Even lights like the AP700 (which cluster a lot of diodes into pucks) have issues with creating a light “cone” which produces strong PAR (photosynthetic active radiation) at the puck’s center, but sharply decreases as you move out to the sides. LED fixtures like the Orphek Atlantik, which spread individual diodes out across the fixture, can create a disco effect of various light colors. This interrupts the natural ambiance of reef lighting and appears artificial. Combined, these issues have led reef keepers to question LEDs suitability as a sole reef aquarium light source. They’ve also fueled new found popularity in seemingly old technology, mainly T5 fluorescent bulbs and metal halides. New dimmable metal halides have found particular popularity among reef keepers. So while LED’s remain the pinnacle of technology (entirely dimmable with adjustable spectrum) they’re place over our reef aquariums is still in question. LED manufacturers have turned to lenses to both diffuse light and blend it better over wide areas of the tank.

The AP700:

The AP700 suffers from the same concerns present with other “puck” style LED fixtures. Kessil uses a proprietary dense matrix puck, which crams lots and lots of diodes into a tight space. The technique creates a very pointed light source and the ensuing cone effect creates a halide like shimmer. Kessil’s color control and management chipset works well, meaning that the individual diodes respond flawlessly to different spectral settings. These range from a dark “ocean-blue” to “sky-white” on up to the yellowish hues of a bright, cloudless day. The AP700 also features a rainbow mode that showcases the fixtures ability to create a multitude of vibrant colors. Like all similar LED systems, the AP700 produces a cone shaped light and corals right beneath the pucks are often hit with a good degree of active radiation, while corals on the out-skirts suffer from much lower radiation exposure.

This leads to concerns about the effect of shadowing on growing coral colonies. Under LED lighting, it’s not uncommon for corals to grow in a specific way, causing other parts of the colony to shadow, seemingly untouchable by the pointed light source. In the small amount of growth, I’ve witnessed over the past few months with the AP700, I can already see some shadowing issues.

So while Kessil’s AP700 does a great job of creating an appealing visual spectrum, it is plagued by the same pitfalls common with similar LED lights. For tanks stocked with moderate light demand corals, it’s likely with some creative placement the AP700 will provide enough needed light. However, with heavily stocked tanks, the AP700 alone is unlikely to meet your lighting demands, unless of course you install a whole lot of them. At roughly $ 900 a pop, that could get mighty expensive.

Control:

Kessil broke away from the control platform laid down by Ecotech Marine, which is arguably the most popular among aquarists. Ecotech’s platform requires the aquarist to either directly connect the dominant light fixture to a computer, or purchase a wireless device which allows the lights to communicate with Ecotech live. Overall, it’s a handy and stable way to wirelessly controlling lighting, which allows the aquarist to log into Ecosmart Live and manipulate their lights from anywhere. Kessil’s system works a bit differently. The AP700 generates its own wireless network, much like smart devices do upon setup. It’s also similar to how a Parrot drone communicates with an iPad. This network doesn’t go away and as long as the AP700 is running, the network is available. To control the lights, the aquarist connects to the network using a smart device (tablet or phone). Kessil provides an app (both on iOS and Android) that gives the user full control over the lights.

Once connected to the network, individual fixtures can be added into a group, making it possible for multiple fixtures to be programmed to respond as one. The programming software doesn’t use preset templates like Ecosmart Live, meaning you can’t simply choose “High Growth” or “Deep Sea Reef.” Points are added along a 24-hour timeline that determine when the fixture turns on, until when the fixture turns off. Each individual point can be altered, adjusting the light’s color (chosen from a color wheel) and intensity (controllable by selecting output percentage). Overall, it takes some getting used to, but once an aquarist is familiar with it, the programming style has some potential.

However, it’s not without some annoying problems. One, smart devices have the bad habit of connecting to the Kessil wi-fi network when you’re near the tank. Just as they would connect to the wi-fi network that provides the best signal, when standing near the aquarium an iPhone or tablet is likely to connect to the Kessil network. This means that you may go to browse the internet and be shocked to see a “No Connection” error, simply because you’re connected to the light’s wi-fi. Also, it seems like many of the programming slots in the Kessil app don’t function correctly. Sometimes the lights turn on at random intervals, sometimes they don’t turn on at all. I was only able to establish a working timeline when using the last programming slot, the others provided intermittent function. While both issues can be worked around, given the price of the lights, I would have expected Kessil to release them with better control software.

I ended up forgetting the Kessil network on my iPhone and only connecting it to the tablet I use as display/control for my Apex, simply because getting stuck on the light’s wi-fi was very annoying.

A hidden strength:

I was highly criticized in my assessment of the AP700’s price, because I quoted a lighting tech that said, “The AP700 is basically two, more powerful A360w lights, built into a single fixture.” After using the lights, I would agree with the tech’s description. The AP700’s pucks have the same build and light quality as the A360W. If you liked the A360’s quality of light, you will certainly be satisfied with the AP700. While some saw this as negative criticism, it actually is one of the AP700’s greatest strengths. Since they are so similar to the A360, it’s very easy to mix and match the AP700 with A360’s to prevent or reduce shadowing and increase overall PAR readings. I ended up mounting my AP700s in conjunction with four A360s and have been able to greatly reduce shadowing, while still maintaining the classic Kessil shimmer.

Final verdict:

The Kessil AP700 falls victim to the same pitfalls as other single source LED lighting options; varying PAR readings and highly diffused light. Like with other LED fixtures, the only way to correct this is either more fixtures or mixing and matching with other lighting types. While they do provide very nice, astatically pleasing light, the control software is far from perfect and not free of annoying glitches. The on board controls are touchy and sensitive, making mobile control a must for programming the lights.

All told, for me to provide adequate light to my 250 gallon reef tank, it’s taken three Kessil AP700’s and four Kessil A360W’s. That’s a total lighting cost of $ 4,300.00. So if you want to invest a lot of money into lighting and demand only the best LED light, the Kessil AP700 is a good choice. If you’re more financially conservative, there are a host of other fixtures on the market that will outperform the AP700 for the price.