Mixed signals.Something about possibly exemption as a " specialty" bulb.
I also believe they can still sell current stockpiles.
Sept. is the month that should add clarity.
Believe NEW rules will be announced.
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Is my light good enough?
- Thread starter nijat11
- Start date
I also believe they can still sell current stockpiles.
Sept. is the month that should add clarity.
Believe NEW rules will be announced.
Was confronted by someone that with reference to this thread said the the inverse square law does not apply to aquarium lights. I helped them understand (or at least I hope that they in the end got it) the limitations of the inverse square law and why it to some degree can be used on aquarium lights.
My hope is that the following will help you understand a bit more as to why you are getting the seemingly odd measurements...
The inverse square law is a law based on an ideal situation where you have a point source radiating uniformly across a sphere. You then have a reading of the amount of radiation that is passing through a section of the sphere at a given distance L from the point source. Assuming that the radiation moving out from the point source is not being absorbed nor reflected, you can then calculate the amount of radiation passing through a given area at distances, r, greater than L. The relation is derived from the formula giving us the area of a sphere is 4*π*r^2.
As we are assuming that all the radiation is conserved, we then get the inverse square law.
Now in the real world we do not have any point sources, but if we are far enough away from the source we can within reason say that it is a point source. That is not the case with any of the lights we are using for aquariums, so we have to make additional calculations (or you discover that your time is far to valuable to sit and play with ray tracing programs and buy a PAR meter)=(1).
Seeing that most people these days are using LED, we can start by looking at them:
LEDs are probably the closest source we have in the hobby to a point source (until you have an array of them), but looking at the inverse square law we already notice a problem with calculations involving LEDs as they do not emit the light uniformly over a sphere, so we have to adjust the law to include the emitting angle (for most LEDs that is 120 degrees). This means that the light falls off as a slower rate than suggested by the unmodified inverse square law, and the smaller the emitting angle the slower the light falls off.
The other thing that makes the measurements more complex is the fact that almost non of the lights consists of just one LED, it is many LEDs in some configuration, so now you are far from looking at a point source which then takes us back to (1).
If we start including reflectors the picture gets even more muddled, and I will leave that to the next section.
The other main type of lights used are incandescent lights and the more traditional fluorescent lights.
They are much closer to emitting the light spherically (tubes do 360 degrees, but are obviously elongated) but are again far from point sources. They are however fairly close to following the unmodified inverse square law as long as the light is not being redirected by reflectors. But most lights of this type do have reflectors and depending on the geometry of the deflector we can then to some degree look at them as being a mix of a point source and what was described above in the LED part of this post, but in the end it brings us back to (1).
As you might have guess looking at a setup with multiple light sources will again bring us back to (1).
As a quick few mental exercises I would like people to consider why this focus on getting the right PAR with a given light, most of the time, ignores the ambient light in the room. Is this not important? and if so, why is hunting the perfect PAR from a light source you are adding on top of an unknown background important?
Why is PAR meaningless without some knowledge of the spectral power distribution in relation to what the plants need?
TLDR: The Inverse square law does work, but for our applications of light, just look at the manufactures spec sheets, get a PAR meter, or just look at how the plants are growing. People in the hobby made it work way before some of use made it more complicated than it needs to be.
My hope is that the following will help you understand a bit more as to why you are getting the seemingly odd measurements...
The inverse square law is a law based on an ideal situation where you have a point source radiating uniformly across a sphere. You then have a reading of the amount of radiation that is passing through a section of the sphere at a given distance L from the point source. Assuming that the radiation moving out from the point source is not being absorbed nor reflected, you can then calculate the amount of radiation passing through a given area at distances, r, greater than L. The relation is derived from the formula giving us the area of a sphere is 4*π*r^2.
As we are assuming that all the radiation is conserved, we then get the inverse square law.
Now in the real world we do not have any point sources, but if we are far enough away from the source we can within reason say that it is a point source. That is not the case with any of the lights we are using for aquariums, so we have to make additional calculations (or you discover that your time is far to valuable to sit and play with ray tracing programs and buy a PAR meter)=(1).
Seeing that most people these days are using LED, we can start by looking at them:
LEDs are probably the closest source we have in the hobby to a point source (until you have an array of them), but looking at the inverse square law we already notice a problem with calculations involving LEDs as they do not emit the light uniformly over a sphere, so we have to adjust the law to include the emitting angle (for most LEDs that is 120 degrees). This means that the light falls off as a slower rate than suggested by the unmodified inverse square law, and the smaller the emitting angle the slower the light falls off.
The other thing that makes the measurements more complex is the fact that almost non of the lights consists of just one LED, it is many LEDs in some configuration, so now you are far from looking at a point source which then takes us back to (1).
If we start including reflectors the picture gets even more muddled, and I will leave that to the next section.
The other main type of lights used are incandescent lights and the more traditional fluorescent lights.
They are much closer to emitting the light spherically (tubes do 360 degrees, but are obviously elongated) but are again far from point sources. They are however fairly close to following the unmodified inverse square law as long as the light is not being redirected by reflectors. But most lights of this type do have reflectors and depending on the geometry of the deflector we can then to some degree look at them as being a mix of a point source and what was described above in the LED part of this post, but in the end it brings us back to (1).
As you might have guess looking at a setup with multiple light sources will again bring us back to (1).
As a quick few mental exercises I would like people to consider why this focus on getting the right PAR with a given light, most of the time, ignores the ambient light in the room. Is this not important? and if so, why is hunting the perfect PAR from a light source you are adding on top of an unknown background important?
Why is PAR meaningless without some knowledge of the spectral power distribution in relation to what the plants need?
TLDR: The Inverse square law does work, but for our applications of light, just look at the manufactures spec sheets, get a PAR meter, or just look at how the plants are growing. People in the hobby made it work way before some of use made it more complicated than it needs to be.
nijat11
Member
Well, still available for sale in the Netherlands.
And in the UK. Although you can get T5 shaped LED tubes that fit conveniently in the old fittings, and are much more economical to run.
nijat11
Member
Hello! Thank you for such detailed answer.
The thing is plants are growing not bad, I will say even good. But I think I have some problem wit coloration, as I cant get full red from Alternathera. I switched to EI dosing, added CO2, added additional flow, adding soil fertilizers, but still something is missing and the only thing that I can think is light.
Here is the attached photo of the tank.
Attachments
nijat11
Member
Hello! Thank you for such detailed answer.
The thing is plants are growing not bad, I will say even good. But I think I have some problem wit coloration, as I cant get full red from Alternathera. I switched to EI dosing, added CO2, added additional flow, adding soil fertilizers, but still something is missing and the only thing that I can think is light.
Here is the attached photo of the tank.
nijat11
Member
bug
nijat11
Member
Thank you I will take a look.
I see it mostly as people wanting to compare their setup with others they find online.
You didn't mention in your explanation the reflections we get inside the tank from the glass boundaries, which as I understand are also very relevant to increase the light density at the substrate level and to move away from the square law and closer to a linear decrease. Of course, they would be counterbalanced by the obstacles in the tank, such as hardscape and even the plants, bringing us back to (1).
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What makes you think it isn't 'full red'? It's colour looks correct in the images you have posted. The top side of the leaves aren't really that red, they are more a pink/orange colouration.
Looks pretty ‘normal’ in colour to me too. Your tank looks great so I wouldn’t be in a rush to change things if it was me.
If it wasn’t growing optimally and all other plants are I’d be more inclined to change the plant rather than the set up. Ludwigia sp red is a much redder plant than alternanthera and also a lot easier to grow.
Same for me, I'd rip them out - it's the "tail wagging the dog" otherwise. Put some nice small crypts like Nurii down the front there.
"Chasing" red can be a nightmare.. From Iron, Genetics, Low Nitrogen, light spectrum, to photoshop manipulations and a few unknowns all can play a part in this..
So lets take a look at this a bit..
One, current stockpiles will be available.
Two there are exemptions for "specialty" bulbs.
The definition (in my opinion) is if the bulb cannot be economically or easily replaced by some other tech. You decide on what that means.
Thought my 2 charts on post #10 would have been mathematically sufficient.. 🙂
Plants use most of the visible spectrum. PAr covers that.. You want to get into PUR (subset of "PAR" or correctly PPFD) Species dependencies and some assumptions are necessary.
Like with green, readily utilized lower in a plant canopy in high light enviroments. Penalizing it (PUR vs PPFD) is somewhat err unnecessary.
now there are major differences in say red algae vs green plants or rhodopsin containing bacteria ect. For our purposes pure "colors" makes little difference. A spread of wavelengths is fine.
You can push morphology i.e stretch, stunt with select wavelengths but it is uncommon in aquariums with "pleasing" light spectrums. Personal preferences of course as to what is pleasing.
nijat11
Member
Okay. I`m here again 😀
I`m thinking to upgraged to chihiros wrgb2 pro.
But I need to choose proper size and amount. Thinking about getting 3x120 pro.
Will it be too much or should be ok?
I`m thinking to upgraged to chihiros wrgb2 pro.
But I need to choose proper size and amount. Thinking about getting 3x120 pro.
Will it be too much or should be ok?
nijat11
Member
Hi all! One more question, I have a good offer for Aquatlantis Easy Lead 2.0. My current led is 4800 lum, according to Aquatlantis their lights 9100 lumens. Does it worth the upgrade?
nijat11
Member
Some opinions please
Want more red, get a light with more red. Hint, it's not the Aquatlantis.
Please restate your full tank dimensions.
A Primer..
How to grow red aquarium plants
How do I get my red aquatic plants to grow more red? Does dosing more iron help ?Different red plants respond to slightly different variables, so one size fits all answers seldom work out. But, there are 3 critical factors that can help you achieve richer, deeper red tones in your planted tank:
www.2hraquarist.com
The best LED units for planted tanks in 2025
What are some of the best LED units for planted aquariums? Can they grow red plants well? Here we review Maxlite Life aqua, ADA Solar RGB, Chihiros Vivid and why they work better than many other commercially available units. Other good choices include the LEDs from Twinstar and Chihiros, ONF...
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Keep in mind that lights get added all the time like Micmol so it certainly isn't and really cant be comprehensive.
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