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 tuned for plant growth in freshwater aquaria.  It has a 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.  I have a “set it and forget it” approach where I pick a colour temperature that looks nice, turn the light up to full intensity (15W power draw) and have the power controlled by a simple electrical plug timer that turns it on in the morning and off in the late afternoon.  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.  The MCR LED has a maximum power draw of 2.8W so in principle the Kessil will be more than 5x brighter.  I don’t know about the actual numerical brightness, but the Kessil is definitely brighter, to the extent that I didn’t really realise how dim the MCR LED was until the comparison.  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.

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 built in heat sinks and those are sufficient for all the cooling the LEDs need so a cooling fan is unnecessary.  This makes the light completely silent in operation.

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.

I feel that 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

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.  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.  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 and have been having a play with that.

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