Today on BRStv investigates we are going to find out if light diffusers have a place in
reefing.
Hi I’m Ryan your host of BRStv investigates.
A weekly you tube series which explores popular reefing theories, products, methods, what
the manuals are missing with a focus on putting them to the test then rate the theory based
on our scale of reef fantasy to reef certainty.
This week we are going to find out if Kessil’s new diffusion kits live up to their claims.
These are small magnetic white lens which snap on to the AP700 and claim to reduce shimmer,
reduce shading or improve spread, enrich color blending and I know everyone is wondering
what impact they have on overall PAR.
If these simple lenses can bring it home on all these claims I think it’s going to really
shake up how many of us approach lighting our reef tanks.
Proper color blending, insane flicker or disco ball effects and shading from the single points
of lights are the biggest challenges LED lighting and reef tanks face, solving all those issues
would be a huge deal so let’s put those claims to the test.
Let’s get right to it.
First thing we would like to put to the test is enriched blending, specifically referenced
as superior color mixing.
This is something that all LEDs struggle with.
With halide and T5 lighting the bulbs emit a wide spectrum of lighting that can cover
anything from UV, to blue, green yellow, orange and red all within the same bulb.
With LED lighting each LED generally hits a very narrow spectrum peak.
To create a full spectrum lighting source you need to use a whole array of different
LED colors which peak at different points and blend them together to create a full spectrum
light source.
There are different ways to do that but the most common is probably to create small clusters
of LED’s which are packed fairly close together with or without lenses and hopefully the color
or light of each individual LED will intersect with each other to create that blended spectrum
of light we are looking for.
However the placement of each individual color LED and reflector or lens will impact the
spread or blending of the individual spectrums.
We have tested a variety lights for this in air and water and it works to various degrees
but there are almost always spectrum hot spots.
In air we use a spectrometer to get the color spectrum at 9 points in a 2 foot grid at a
few heights.
This is an example of a typical cluster of LED’s that don't use lens a foot above the
sensor.
You can see there are pretty major changes in spectrum at the each measuring point.
Same with a typical cluster of LED’s that uses lenses.
In fact I would say in this case the spectrum hot spots with lenses are a bit more pronounced
I’ll share these because color blending is one of the things that Kessil has always
claimed to do particularly well without the diffusion lenses.
Their approach is what they call a dense matrix array where they pack all of the LED’s under
a single lens which in theory will blend all of the colors together into a single blended
spectrum without the spectrum hot spots.
We put that to the test with the spectrometer and I have to say the shifts in spectrum at
the 9 different locations in the 2 foot grid are significantly less dramatic but still
not perfect.
We threw the slight diffusion kit on and repeated the test.
Sure enough the results are pretty impressive; the changes in spectrum are amazingly subtle
between all 9 points.
Same can be said after we put the major diffusion kit on, this time the improvement is a bit
more subtle but the spectrum is extremely uniform all points.
We also like to test spectrum in water because water and ripples serve as their own type
of lens and changes how the light behaves.
Because it is difficult to measure spectrum under water and it changes rapidly we are
just looking for visual cues in a pretty extreme environment where it’s easy for the human
eye to see significant issues which is a white background in a shallow tank.
Again for reference point this is what some of the common LED clusters look like with
and without lenses in this environment.
You can see rather than the optimal blend of spectrums are looking for it is pretty
typical for the ripples in the surface of the water to act as their own lens and shot
the individual spectrums all over.
How impactful that is largely based on how many ripples or lenses you create with your
tanks flow patterns.
You can see if I reduce the ripples the impact is reduced and at least to the human eye the
blending seems to be better.
I guess how it is reaching the coral is up to some debate.
Most of you certainly won’t be able to catch this with the human eye on multi colored background
like a standard aquascape and by the time it reaches the bottom of a two foot tank the
colors are blended better on the sand.
However many of you might be able to see this impact on the back of the tank where you can
see the individual beams of spectrum dancing around on the back of the tank like fire.
So this is how the Kessil performs in this pretty extreme environment with a tremendous
amount of ripples, shallow tank and white background.
Similar to the spectrum tests in the air we did a minute ago you can see putting all the
LED’s under a single lens is a significant improvement and already performs fairly well
in this regard so how do the diffusion kits work.
After snapping on the diffusion kits I would call the slight diffusion kit almost perfect.
I don't see any random bits of color dancing around the tank and all of the individual
color LED’s seem to be blended flawlessly into a single spectrum of light.
Snapping on the major diffusion kit has a very similar impact and to my eye looks even
better but honestly it is hard to tell the difference and I may only think it looks better
because it says the word major on it and it is supposed to do it better.
All in all I have to say these frosted diffusion its are achieving the claim of better spectrum
blending both as tested by the spectrometer as well as visually.
Similar to that is the claim of reduced shimmer.
One of the perceived draw backs of LED’s is a pretty overwhelming volume of shimmer
which is commonly referred to as the disco ball effect.
This can range from slightly annoying flicker, to disco ball effect all the way to what I
would call a static TV effect which is obviously less desirable.
There is no way around it the more individual LED’s or lenses you use the more the shimmer
will transition into flicker.
Once more Kessil is already well known for having arguably the best shimmer effect of
any LED on the market because of that dense matrix array under a single lens but that
is still too much shimmer for many people.
I’ll admit that I’m one of those people and why I prefer to soften that shimmer by
supplementing with T5 lighting in most cases.
So we already saw the shimmer in the most extreme environments when we looked at spectrum.
This time I’d like to look at them in the BRS160.
We turned on just a single AP700 and turned the T5’s off.
This is what the shimmer looks like on average.
The flow is variable in this tank so it won’t always look the same.
If you are paying close attention to the tank this is probably more than most people would
like.
So how do the diffusion kits look well the slight diffusion absolutely softening the
shimmer lines and making the effect less dramatic?
Something probably best seen side by side.
I think most people would agree the diffused version of shimmer is more appealing.
Again the major diffusion to me seems to be a minimal improvement over the slight diffusion
but I’ll let you decide.
Again I am going to have to say Kessil claim of reduced shimmer is accurate.
The third claim is reduced shading specifically, diffusing the light to reduce intensity or
PAR hot spots and spreads the light more evenly and at shallower angles.
Which is especially good for branching species like corpora, Millipore, Stylophorum?
The Easiest way to test the spread and hot spots is just to test a PAR grid with and
without the division lenses.
We will do that by taking a quick look at the average of the center 6” ring, middle
18” ring and outer 30” ring with no diffusion as well as the Slight and major diffusion
kits at multiple depths.
With the light 6 inches above the tank and at a depth of six inches we saw an average
PAR in the center 6” of 347, middle 18” ring a par of 194 which is a 44% drop off
and outside 30” ring had a par of 88 which was 54% drop off from the center ring.
These results are pretty typical of measurements taken at shallow depths with LEDS which have
compact pucks or light sources where the PAR will always be highest where the two light
sources intersect in the center.
At a depth of 12 inches that evens out pretty dramatically with an average par of 220 in
the center 6 inches, 171 in the middle 18” ring which is only a 22% difference, 122 in
the outer 30 inches and a drop off of 28%.
Overall I wouldn't define this as a significant hot spot because the fall off is pretty even
over a 30 inch spread.
At a depth of 18” we are seeing an average par in each ring of 163.
157 and 127 which is a fall off just shy of 4 percent and 13% from the middle.
This is what I would call pretty flat lighting and going to be hard to improve on.
So let’s try the slight diffusion kit.
Which at 6” deep had par readings of 220, 127 and 61 respectively.
This equated to a fall off of 42% in the middle ring and 51% which is better than the 44 and
54 percent fall off without the diffusion kits but just barely.
You will however notice the significant drop in par which we will cover in just a moment.
at 12” deep we saw 154 ,114, 81 which was a fall off of 25 and 28 percent which was
almost the same percentage is no diffusion kit but the fall of the middle 18 inch ring
was actually slightly higher.
at 18: deep we saw par levels of 114 107 , 96 in the respective rings which was a drop off
of 6 and 10% again was a very similar fall off to no diffusion by percentage.
I’ll save the suspense and other than a minuscule reduction in PAR the major diffusion
kit also had about the same fall off of 41 and 48% at a depth of 6”, 23 and 24%at 12
inches deep and 5 and 14 % at 18 inches deep.
In this case I have to say it’s my opinion that Kessil’s diffusion kits did not live
up to the claim that they are providing better spread and based on these numbers I don't
see how it could provide a significant improvement on the impact of shading.
We also saw a pretty sizable impact on par output which is the next point
In relation to par we just took an average of all 36 par measurement points’ at all
three depths which is 108 points.
With no diffusion kit the AP700 has an average 108 point par of 149, with the slight diffusion
kit average of 99 and 94 with the major diffusion lens.
Which means the lenses resulted in 33 and 36 percent reduction in par?
So on a rating of reef fantasy to reef certainty and the three major claims of enriched color
blending, reduced shimmer and reduce shading or improve spread I am going to give this
a 6.6 two elements are pretty much a certainly with improvements on shimmer and spectrum
but the spread or shading claim was a fantasy in my eyes.
PAR is obviously going to play a big role here and some of you might on be interested
in these diffusion kits because of the 30ish percent reduction in PAR output.
I will say based on these results we decided to throw the major diffusion kits on the BRS
160 because we run only run the Kessil at 30 anyways.
The improved shimmer and color blending is worth the relatively small increase in power
consumption by turning them up to 40% or so.