Potatohead
Valuable Member
It's not about PAR, it's about shadowing and coverage.
LEDs are NOT a cost effective way to light a reef... (at least not for me)
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It's not about PAR, it's about shadowing and coverage.
Plasma is broad spectrum...... nobody denied spectral differences don't have consequences..
Point was giving the exact same spectrum.. "photons are photons"..
http://www.advancedaquarist.com/2013/2/aafeature
image apparently is blocked
There are broad spectrum whites that would better match the plasma spectrum.. and if run at equal quantum output "should" show no differences..
BYW.. few lights of any kind in popular use emulate plasma either..
sure you might even find the same difference w/ heavy actinic/blue t5's......or high K MH's
ONE of the reasons "broad spectrum" LEd's are in vogue..
also helps to read the whole thing:
Like I say.. "It's complicated"...
Point was giving the exact same spectrum.. "photons are photons"..
http://www.advancedaquarist.com/2013/2/aafeature
image apparently is blocked
There are broad spectrum whites that would better match the plasma spectrum.. and if run at equal quantum output "should" show no differences..
BYW.. few lights of any kind in popular use emulate plasma either..
sure you might even find the same difference w/ heavy actinic/blue t5's......or high K MH's
ONE of the reasons "broad spectrum" LEd's are in vogue..
also helps to read the whole thing:
Like I say.. "It's complicated"...
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Bouncingsoul39
Valuable Member
Does the possibility of differing spectra invalidate the results of the study in your opinion? If photons are photons, then the spectrum shouldn't matter, correct?
In the videos they measure PAR at different depths at multiple points in each tank. If you compare the values obtained with LED's and MH for example, the PAR values through the tank may be somewhat more variable than with the MH - but there were hot spots and variability with MH as well. The PAR coverage was exactly the same. Corals are able to adapt to a Huge range of PAR. The only point being - that contrary to those who (here) seem to be saying that there is a big difference between different types of lighting systems, looking at actual data doesn't suggest that big a difference. I guess (getting back to the topic of the thread) - I havent seen anything that convinces me of the OP's theories.
no, it doesn't invalidate anything..
How many reef tanks are run under a pure "daylight" spectrum?
I already (and am not alone in this) that it implies matching spectrum's a bit.. Most common lighting is fairly uniform in that regard Heaviest blue to heavy blue..
Nothing like the plasma.
Study is more akin to outdoors vs any "common usage"artificial light source...
a better argument is MH's should be around 6500k ...
Has nothing to do w/ LED per se.. Just w/ any light w/ a similar spectrum..
From the Study: >>The results obtained during this study reveal that the effects of spectrum and irradiance on coral growth are highly species dependent, which underscores the need for species-specific optimization of aquaculture. At present, different coral species are aquacultured under similar conditions, which clearly is not optimal.<<
The data from this study do not seem to apply to an aquarium setting in that you only have 1 light source - and youre putting multiple corals in your tank each of which grow best under certain spectra and light. There is no possible way to analyze each coral and place them in a certain place in the tank - and at the same time make sure they are receiving the optimum amount of light. If you read the last sentence in the quote above it probably answers why every person has a different perepective on lighting an aquarium - because some people have the right species of coral under the optimal spectrum and intensity - and they grow well - where another Aquarist may not be as successful. The issue is the livestock - not the light. There is NO light that will give ALL inhabitants the light appropriate For their maximum growth.
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Potatohead
Valuable Member
It looks uniform when there is nothing in the way blocking the light, sure. Let's take those same types of measurements in a normal tank with some colonies in it and there is a substantial difference.
A360
AP700
T5
Bashing LEDS, given then level of frustration that many people who have used them have is understandable and a large portion of the blame should be assumed by the manufacturers for not doing a better job educating their consumers. As I have said previously, I am a light agnostic but I do have a preference for MH as its a system I know like the back of my hand and really love the look of. Last year I scored a set of Hydra 52 HDs and I didn't bother taking all of the warnings about par level seriously. Predictable results were forth coming. As a knee jerk reaction I scored 3 Radion Gen4 Pros for a 48" tank at my office at work and once I got my head out of my a** and got a little advice from @saltyfilmfolks on setting them up as well as a little more information about nutritional tweeks that might help (more N03 / P04) for a couple of months I saw results that certainly rivaled MH. At home I run a Spectra with Radiums, B+ T5s and a couple of reefbright strips mainly because I love the look and ease and performance of Radium bulbs. So as an unbiased observer who uses all of these lights and have had his share of issues with them all, I am convinced that many people are dumping LEDs and going back to MH / T5 because either they don't seem to be able to get them tuned in or they are hitting hotspots on the emitters. Again, this is absolutely the manufacturers fault for not doing a better job educating their consumers. I think at least Echotech is trying with the coral lab profiles and the new diffuser mod.
True dat.
That.
I have to agree with the use of the words @jada has used. Nuances.
What par level is targeted and where. What is the DLI goal. What reflectors and fixture is the MH in and how bad is the hot spot from it. I have two fixtures. One is smooth with a spot in the middle from bulb and proximity one was an 800 fixture with spot so bad you can see it on the lid.
How much intensity is lost with the reflector being mirrored , stippled, or multi faceted.
As far as shading we still haven't adrees that most folks are probably using their light wrong. Why would you take a puck pendant light and point it strait down on the tank. Why not move it to the edges and point it back at the corals. Front light back light. Back light fill. Lol.
If you can find an led light that matches the par of the mh , it's usually 8x12 max rather than 16x16.
It looks uniform when there is nothing in the way blocking the light, sure. Let's take those same types of measurements in a normal tank with some colonies in it and there is a substantial difference.
A360
AP700
T5
What is the context of that article? Clearly, the more light shining down, the less shadows underneath. Whats the point? If the PAR value at Point A in a tank is 400 under Metal Halide and 400 at Point A in an LED tank, the shadowing would be the same. This is showing 3 of the same coral groupings illuminated under different light intensities. Without knowing the definitions of the lighting on the right pictures and left pictures its difficult to see your point
Lol. We agree. Common sense is usually to blame.
To many buttons on leds. If an led just came one at a single intensity folks would have a lot more success.
Btw. That salty guy is a hack.
Look at @WWC tanks. They grow more than a few acros under LED.
Also this is from the article posted above:It looks uniform when there is nothing in the way blocking the light, sure. Let's take those same types of measurements in a normal tank with some colonies in it and there is a substantial difference.
A360
AP700
T5
>>Although the beneficial effect of light on growth was limited, it is important to state that the colonies used in this study were small enough to prevent self-shading. When colonies increase in size, a self-shading effect occurs where the lower and inner parts of colonies receive less light as higher branches create shade (Titlyanov 1991). For such colonies, a higher beneficial effect of light on growth is expected. As aquarium corals are usually kept relatively small, self-shading effects may be less prominent in captivity.<<
Not quite true. Led lenses are needed to increase power. They create a signature quality. Narrow heanterall and sharp quite often.
The difference is light bulb Vs flashlight.
No truer words...
Potatohead
Valuable Member
Uhh, no.
I put what lights they are above the pictures. They are not only different intensities.
Those screen shots are from a BRS video a few months back comparing the shading of different light sources. Single point LED, dual point LED, reflected fluorescent. There is a big difference between them and the only way around it with LED is to add more fixtures. This is where the cost and energy savings argument starts to fall apart.
Or choose a more appropriate fixture from the start.
Here are some PAR values from BRS TV (Radion G4XR30, 24 inch cube tank 12 inches deep) vs. (spectra 400w also at 12 inches deep - same tank)
What is the LUX reading on the bottom of each picture mean? Rather than saying 'Uh no', can you explain?
To keep it in context , how big and how heavy is that 400 w fixture? My point was the led is tiny so figure out how to position the light correctly to avoid shading. W a large fixture that's tough. With an led it's easy. But most still default to the hang it directly over the tank directly over the coral.Here are some PAR values from BRS TV (Radion G4XR30, 24 inch cube tank 12 inches deep) vs. (spectra 400w also at 12 inches deep - same tank)
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