Kessil A80 'Tuna Sun' passive cooling LED light
Kessil A80 ‘Tuna Sun’

The Kessil A80 ‘Tuna Sun’ is the smallest size LED light Kessil sells with a spectral output optimised for plant growth in freshwater aquaria.  It has both tunable spectal temperature (from red to blue/white) and tunable intensity.  There are terminals that can be connected to a 10V supply to control the intensity electronically.  Kessils are expensive but have a reputation for high quality so I figured I’d splurge when replacing the MCR LED light that came with the Oase biOrb aquarium. 

Kessil A80 brightness

The Kessil is rated to a 15W maximum power draw, so relative to the MCR LED the Kessil can be more than 5x brighter.  I didn’t really realise how dim the MCR LED was until the swapping out for the Kessil.  It’s not obvious what is meant by “low” vs. “medium” vs. “high” lighting in an aquarium.  There is discussion of ‘PAR levels’ which is a brightness + spectral characteristic measure (primer here from Osram).  Regardless, Kessil doesn’t play that and doesn’t provide any PAR characteristic measurements for their lights.  That being said, it’s not just the lighting intensity but the quality of the spectral characteristics that determine plant growth and I’m very happy having made the switch.

Installation and passive cooling

Installation was pretty straightforward:  the MCR LED is removeable and sits in a plastic collar over a plastic holder that covers the hole in the top of the aquarium and I lifted off the MCR LED and sat the Kessil A80 on there instead.  The Kessil is slightly larger so it doesn’t fit down into the hole, but does sit relatively stably and flat on top, which for me is fine.  You can see the before and after in the pictures of the hygrophila polysperma – the intensity difference doesn’t come out at all in those photographs so you’ll have to trust me on that.  The Kessil also comes with a gooseneck mounting system for use on aquaria with exposed tank rims.

What I really like about the A80 in addition to the nice quality of the colour and the brightness of the light is that the LEDs are passively cooled – the light has large heat sinks integrated smoothly into the design which means a cooling fan is unnecessary.  The lack of any moving parts may help with durability and, as a really nice feature, the light is completely silent in operation.  The passive cooling really works – even at full intensity the top of the A80 gets warm but not uncomfortably so and the light stays cool on the bottom.  I was initially worried that having it sit flat on the plastic lid of the tank would cause overheating and potential damage, but there’s been no issues whatsoever in actual operation.

Improved plant health with better lighting

Upgrading the intensity of the light provided was a major factor in the success of plant growth in the aquarium, particularly the marsilea carpet which struggled mightily to gain any ground at all under the dimmer lighting conditions. Even with the Kessil sitting right on the top of the aquarium (and not suspended over it) the Kessil is 5 cm above the surface of the water, and then the light has to shine through an additional 40 cm of water to get to the carpet so there is considerable attenuation on the way down.

Kessil makes a big deal of the “shimmer” effect you can get using their lighting.  For me this is neither here nor there and in fact I didn’t notice it at all until I moved the powerhead close to the surface of the water, where the movement of the water surface then caused the shimmer to happen.  Currently I have the powerhead back down at a much lower level in the water mainly to keep it from blowing around the ludwigia too vigourously, so most of the shimmer has been lost and isn’t really missed if I’m honest.

Controlling the Kessil LED

Two choices here:

  1. Set it and forget it

You can operate the Kessil A80 perfectly fine with a standard household mains timer, in which case it can be automatically turned on and off.  Using the two manual adjustment knobs on top of the unit, pick a colour temperature that looks nice, turn the light up as high as you’d like and have the power controlled by a simple electrical plug timer that turns it on in the morning and off in the late afternoon.  The transitions between unlit and fully lit are quite abrupt and have a quite dramatic effect on on the behaviour of some types of fish when the light turns on and again when the light turns off.

  1.  Use an electronic controller 

The A80 light intensity and colour can both be regulated by 0-10V inputs through a stereo-type patch cable that plugs into the top which lets you get relatively smoothly changing gradients of both light and colour through the day if you add a dedicated programmable controller.  These are not cheap, but I picked one up on Ebay for not excessively much.  After some experimentation, I’m now convinced getting the controller is worth it.  Being able to easily tweak light intensity and duration is pivotal in the effort to get green algae under control.

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