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Discussion Starter · #1 ·
OK, I decided to design and make LED lighting for my tanks. I have two identical 40 gallons tanks, one stands in a room filled with daylight, another in a room with a single tiny window. They have identical compact fluorescent lighting, filters, similar fish and plants (quite demanding), identical water composition, CO2 and fertilizing, but the first tank flourishes, the second barely survives continuous algae problems. I am weekly measuring nitrates, phosphates, magnesium, calcium, potassium, sodium and chloride ions - they are the same and reasonable.

Yes, I did try a commercial LED fixture to no avail - some plants became white, some just died, algae flourished. I got very annoyed, bought a scientific spectrometer, measured the fixture's spectrum and found it unacceptable. Then I went to several aquatic stores, and measured spectra of many other LED fixtures, including $600+ ones (with store-owners consent, of course), and they were essentially all the same as for the one fixture I tried. I am intentionally omitting the brand names, this is not an advertising. But I am determined to make a LED fixture that works better. I need to do the research first, and will be posting my accumulating knowledge here, in hope that it may help someone else.

Aquatic plants use light for two purposes: Photosynthesis and Decision-making (when to germinate seeds, produce shoots, bloom etc.). The sun produces electromagnetic waves with wavelengths from about 290nm to 3,200nm. Plants use mostly the 400-700nm part of the solar spectrum, which is called PAR (Photosynthetically Active Radiation).

The ratio of energy in the PAR region (400-700nm) to total solar radiation is around 0.5. It is nearly independent of atmospheric conditions.

During photosynthesis plants absorb CO2 (molecules consisting of one Carbon atom and two Oxygen atoms), use the carbon atoms to make their tissues (to grow) and release the remaining oxygen. However, plants also breathe, or burn their carbon reserves to obtain energy for various things they need to do. Breathing (respiration) consumes oxygen and releases CO2 back into the environment. A condition when amount of CO2 taken for photosynthesis is equal to the amount of CO2 released during respiration is called Compensation Point. If there is not enough light for the photosynthesis to be faster than the respiration, plants will use carbon from their tissues to breathe, they will inevitably run out of the carbon and will die. Low-light plants use the light more efficiently and their Compensation Point is low. Hight-light plants need a lot of PAR to achieve the Compensation Point.

On the other side, plants can not photosynthesize with indefinitely fast speed. If the amount of the light keeps increasing, the plant will try to grows faster. However, eventually, light intensity will increase up to the point when plant's photosynthetic machinery can not keep up. This is called Saturation Point. Having a fixture with light intensity above the Saturation Point is not only wasteful, it is very bad for plants growth.

Light is not a benign thing, it makes the life possible, but it always produces free radicals, which indiscriminately destroy various complex molecules used for photosynthesis and other life processes. So, while photosynthesizing, the plant also continuously repairs the light-induced damage. At lighting intensities above the Saturation Point the plant may become Photoinhibited and eventually die.

Not all 400-700nm PAR is equally good for out tanks. We all want to grow more advanced (Vascular) plants, not the algae. Our plants mostly need blue (400-500nm) and red (630-700nm) light, because they harvest energy using mostly Chlorophylls A and B. However, Nature did not waste the remaining yellow and green energy, this light is often used by algae. For example, in many cyanobacteria the main light-harvesting pigments are two phycobilins, rather than chlorophylls, they use bands in 550-615nm greenish-yellow-orange region.

Additionally, plants produce very important pigments called Carotenoids, they neutralize the photo-damage and need blue-to-cyan (430-520nm) light to function.

Also, I must make sure my fixture has wavelengths not only for photosynthesis, but for the plant's Decision-making (see above).

The task is complicated by the fact that not all wavelengths can be achieved using LEDs existing to date. Also, aquarium walls are transparent, this makes it possible for the light energy to be lost in the room. Also, I need to make sure there are no dark spots in the tank.

Therefore, I need to make research and decisions on:
1. Optimal light intensity
2. Optimal light spectrum
3. Technical issues

I am going to do the "Optimal light intensity" research first and will post it once I have something useful.
 

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one stands in a room filled with daylight, another in a room with a single tiny window.
but the first tank flourishes, the second barely survives continuous algae problems.

I got very annoyed, bought a scientific spectrometer, measured the fixture's spectrum and found it unacceptable.
The tank receiving daylight has the algae issues?

What meter did you buy?

How are you measuring PAR?

Optimal light intensity would be in regard to the plant species you wish to grow?
 

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Discussion Starter · #4 ·
To Maryland Guppy:
Growing IS difficult, it does not depend 100% on you, my post is highlighting this!
Nature is so very much more complex and interesting than you think. Arrogance is not appropriate here.
1. No, the tank with daylight is flourishing, did you even read my post?
2. I purchased ASEQ Instruments, LRI-B (V1.0, 16 bits). This is a spectrometer for 190-1300nm range. It was calibrated at NIST in mequivalents/(m2*sec) - a scientifically accepted units for measuring RAR.
3. I am RESEARCHING the optimal PAR for high-light demanding plants, once I am ready, I will post details for everyone to use.
Again: My hope and goal are to help myself and people here to grow beautiful plants, not to boast how easy it is for myself to grow.
 

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To Maryland Guppy:
Growing IS difficult, it does not depend 100% on you, my post is highlighting this!
Nature is so very much more complex and interesting than you think. Arrogance is not appropriate here.
1. No, the tank with daylight is flourishing, did you even read my post?
2. I purchased ASEQ Instruments, LRI-B (V1.0, 16 bits). This is a spectrometer for 190-1300nm range. It was calibrated at NIST in mequivalents/(m2*sec) - a scientifically accepted units for measuring RAR.
3. I am RESEARCHING the optimal PAR for high-light demanding plants, once I am ready, I will post details for everyone to use.
Again: My hope and goal are to help myself and people here to grow beautiful plants, not to boast how easy it is for myself to grow.
Sorry you didn't like my signature.

1. Just verifying the sunlight theory. With so much wind in one's sails I had to validate the presented content.
2. Is this meter really worth the expense? Do you plan on marketing an LED fixture?
3. Many are already familiar with PAR ranges for many plant species, again what plants peak your interest?

There is an excellent plant finder on this site with detailed descriptions.
Many more on other sites too, to help in plant selection and suitability for one's tank.

Many sites still post in watts/gallon, by today's standard it doesn't help much.
Wish they all listed PAR ratings instead, but who is going to re-write it all?

Many are using commercially available LED fixtures and growing quite well.
Granted they are covering their tanks with more than 1 fixture.
T5HO is still very popular and many won't transition to LED due to excellent growth.
MH is still be used used in planted tanks.
All the more reason for a "PAR" preference for aquatic species.
 

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Discussion Starter · #6 · (Edited)
No Marketing. The meter is an overkill for most people here. Also, the meter's software is awkward and unreliable, I am only able to use it because my spouse is a computer/electronics engineer. This is why I originally did not post the meter's brand name.

I am driven by curiosity here. I hope to accumulate info useful without buying anything at all.

I live in the area with several excellent aquatic stores. Their marine tanks are breathtaking, their freshwater tanks are depressing, and they all use "the best" LED fixtures available. I often see white plants with LED fixtures, while cyanobacteria is happy. This is NOT iron/nutrients deficienciy. I came to think it is from LED lighting (a very strong 460nm band not compensated by other wavelengths). I just want to get to the bottom of this. If I, indeed, succeed with the fixture, I may offer it for the display tanks in these aquatic stores. I am very far from the success yet.
 

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None of us try to offend other people here. Some of us inadvertently offend others when jokes, subtle or otherwise, get taken too seriously. Please concentrate on what you have to offer, whether advice, experience, test results, etc., and ignore the extra words.

I will be watching the results of any tests like this with great interest!
 

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You signature indeed feels offensive.
People come here to solve their problems, no need to patronize them.
Offensive it shall be. [smilie=b:

We all have "problem plants".
One cannot grow everything, it just won't happen.
My failures start with soft water plants, low KH & low pH.
Do I really want to change everything, maybe not.
There is enough species I can maintain very well with my existing water parameters.

Often try to help others solve their issues provided they give enough good information.

[URL="http://spectra.1023world.net/"]http://spectra.1023world.net/[/URL]
A useful LED tool that can be used for estimation.

PAR is one thing but if the PUR rating doesn't go over 70% I have my doubts.
Seneye has a Reef monitor that provides PAR and an estimated PUR rating in V2.0 firmware.
A useful tool for just under $200USD.

Don't discount the reef sites either.
There are some fine LED builders out there!
O2surplus & Theatrus on Reef Central.
They build many driver boards and LED puck arrays. Planted tank options too.
 

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on behalf of my pal Marylandgoopy he is a member who has helped me many times over the years, his signature only spills truth. Also its a "blanket statement" so you cant just immediately assume hes talking about a specific plant or person etc.

 

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Discussion Starter · #11 ·
Sorry guys! I did not mean to hurt anyone's feelings. I need your help and input and I love the site.
 

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Discussion Starter · #12 ·
Optimal Light Intensity.

According to a 2006 paper in Limnology and Oceanography (Volume 51, N 6, 2006, pages 2722-2733), 15 mixes of various densities of the following aquatic plants were created:
Low light species: Vallisneria Americana "Natans", Vallisneria Americana "Gigantea", Sparganium Emersum;
Medium-low light species: Hygrophila corymbosa "Stricta", Sagitaria Platyphyla;
Medium light species: Sagitaria Subulata, Myriophyllum aquaticum, Egeria densa, Potamogeton Crispus, Potamogeton Pectinatus, several Callitriche sp.;
High light species: Cabomba caroliniana, Hygrophila corymbosa "Aroma"

Average Compensation Point was achieved at 119 μmol/(sec m2) of PAR
Beginning of Saturation was achieved at 455 μmol/(sec m2) of PAR
The actual Saturation Point was not achieved and is probably is 20% higher, at 546 μmol/(sec m2) of PAR.

A very good news is that we can approximately convert these values into W/m2 of light for out tanks simply by dividing them by 4.6, thus we receive:

Average Compensation point - 26 W/m2 of PAR
Beginning of Saturation - 99 W/m2 of PAR

We can do this because in 1972 K.J. McCree (Agric Meteorol, Volume 10, pages 443-453) published that 1 W/m2 (PAR) = 4.6 μmol/(sec m2) (PAR) for the Sun, metal halide bulbs, and fluorescent bulbs.
While this was a long time ago, the same coefficients are still used in modern scientific literature. There were no commercial LEDs in 1972, but for white LEDs I think that the same 4.6 conversion coefficient may be assumed for now.

Now we can convert to W/gallons for our tanks. For example, my 40 gallons tank is 12 inches wide and 48 inches long, so the water top surface area is 12x48=576 square inches, which equals to 0.372 square meters (used Google to convert this). Therefore, for my tank with the same plants:

Average Compensation point - 26 W/m2 * 0.372 m2 = 10W of PAR, or approximately 0.25 W/gallon of PAR
Beginning of Saturation - 99 W/m2 * 0.372 m2 = 37W of PAR, or approximately 0.92 W/gallon of PAR

But these are not Watts of electricity consumed by our light fixtures, but of light energy this fixture produces.

A light source transfers electric energy into light and heat. When buying a light source we need to look at its actual power (often presented in a small font), not the fashionable and large-font-ed power of an incandescent bulb producing the same amount of lumen. Then we need to find out how much of this power is actually transformed to light.

At https://www.dial.de/en/blog/article/efficiency-of-ledsthe-highest-luminous-efficacy-of-a-white-led/ there are theoretical maximum energy conversion efficiency for several light sources:
T5 fluorescent, 54W: 23.7%
Metal Halide, 70W: 31.5%
Warm white LED, 35W: 42.3%
Cool white LED, 16W: 48.7%

According to a 2009 paper in Nature (Volume 459, pages 312-314), fluorescent lighting transforms 10-15% of the input energy into light. According to Chapter 4 of a modern textbook "Energy and Fuels in Society" by Ljubisa R. Radovic from Penn State University, typical efficiency of a fluorescent lamp is 20%.

According to data-sheets of several LED manufacturers (Lumileds, LedEngine and Luminus) their LEDs transform 17 to 63% of inputted electrical energy into light. It is an awfully wide range! Once/if I come to the technical parts of this project, I will buy a few dozens of LEDs with appropriate PAR wavelengths from several manufacturers, measure their actual spectra and actual efficiency and will post it here.

Metal halide lamps imitate the Sunlight better than fluorescent and LEDs light sources (Wang W. Simulate a "Sun" for solar research: a literature review of solar simulator technology. Stockholm, Sweden; 2014). Unfortunately, efficiency of metal halide lamps depends on their power, those used for stadium lighting are highly efficient, but those for aquariums not so much.

Based on the above data, my best (and I believe pretty good) guess of average efficiencies of modern aquarium fixtures and light bulbs are:
Fluorescent: 20%
Metal Halide: 25%
LED: 40%


From here, can be found that to achieve the 10W (0.25 W/gallon) Compensation Point (plants barely alive and not for long) in my 40 gallons tank I would need:
10W/0.2= 50W (electricity) fixture if using fluorescent lighting
10W/0.25= 40W (electricity) fixture if using metal halide lighting
10W/0.40= 25W (electricity) fixture if using LED lighting

To achieve the 37W (0.92 W/gallon) beginning of Saturation (plants happy) in my 40 gallons tank I would need:
37W/0.2= 185 W (electricity) fixture if using fluorescent lighting - 4.6 W/gallon (electricity)
37W/0.25= 148 W (electricity) fixture if using metal halide lighting - 3.7 W/gallon (electricity)
37W/0.40= 93 W (electricity) fixture if using LED lighting - 2.3 W/gallon (electricity)

Most of the plants discussed in the publication's set-up have low and medium light requirements. I think that aquariums densely planted with light-hungry species will need twice more light, but it is just a guess.

I wish people here would post their light fixture type, electrical wattage, and list of plants that grow well at these conditions, then the actual practical values could be calculated and added to the Plant Finder.
 

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ive got a 6 bulb 4ft agrobite T5HO with 6500k daylight bulbs (getting aquafloras l8tr on) substrate is 3 1/2" thick, high light plants only. Light is 12" exactly from rim of tank, tanks a standard 40b. I calculated once how many wpg i have but i forgot. think it was like 9.
 

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Does that very interesting, long post discuss PAR at the water surface, at the substrate surface, or an average intensity in the tank? The PAR from any light source drops off with distance from the source.

Our PAR meters all read in micromoles per square meter per second, so I think it is best to always refer to PAR using that scale. But, how do you decide on what level in the tank you should be measuring PAR and relating it to low light, medium light, etc.?
 

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Optimal Light Intensity.

I wish people here would post their light fixture type, electrical wattage, and list of plants that grow well at these conditions, then the actual practical values could be calculated and added to the Plant Finder.
This would be a tall order.
Commercial lights have recorded PAR data points, if a manufacturer doesn't post their PAR data it seems bogus to me.
Someone would measure it and post their findings anyway.

For DIY builders all fixtures are different.
Wattage would not be relative to PAR data, different angle LED lenses affect this greatly.
Dimming capabilities can also alter light output.
Running an LED at reduced mA's can alter output too.
PWM dimming @ rated output offers the most constant display of light while allowing dimming capabilities.

Being a DIY LED type, I have settled on a puck design that is over all my tanks.
It requires dimming else there would be an algae farm!
 

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Discussion Starter · #16 ·
Wow, thank you! It is becoming useful!

DutchMuch, according to Hydrofarm website (https://www.hydrofarm.com/p/FLT5464BK20) your light bulbs are 54W each. Also, according to the spectrum from their web page, all the light is produced in PAR region. Have I found the correct bulbs? A am sorry for asking a stupid question, but does "standard 40b" mean 40 gallons? (I immigrated to US and English is not my mother-tong)

If yes, then the calculations work and you seems to have perfect light for your high-light plants!

For DutchMuch tank with light-demanding plants:
54*6=324W of Electricity, which for his 40 gallons tank means 8.1 W/gallon Electricity
324*0.2=65W of Light, which for his 40 gallons tank with fluorescent lighting means 1.6 W/gallon Light (PAR)
65*4.6 = 299 μmol/sec of light, which for his 40 gallons tank means 7.5 μmol/(sec gallon) of Light (PAR)

If his 40 gallon is like mine 40g, with approximately 0.372 square meters of the water surface, he has
299 μmol/sec : 0.372 m2 = 804 μmol/(sec m2) (PAR)

The paper in Limnology and Oceanography (described above) found that for their, mostly low to medium light plant collections, the Beginning of Saturation happened at 455 μmol/(sec m2) of PAR, your practical value is almost twice higher, which makes perfect sense!

Hoppycalif: This post is so far about the PAR at the water surface per a square meter of this surface and it assumed that essentially all light energy produces by a bulb is directed into the aquarium. We need to start from somewhere.

I have not done proper research yet, but I strongly suspect that the distance to the water surface, substrate height and aquarium depth are all so very important, because we need to direct all the light into the tank and to KEEP it there. In reality, the light is emitted in all directions and is continuously absorbed, reflected and refracted from the fixture, plants, water and aquarium walls surfaces. I think that the energy of a direct light ray absorbed by the air and water column between the air and substrate (tank height) is much less then the energy continuously absorbed and reflected by plants, walls and fixtures. I will do the research and know more, at the moment I am not able to better answer your questions. But I want to find out about optimal spectral wavelengths first (just very curious about it), and only then will go into technical details.

My reading of scientific literature has been very frustrating, because (unlike the authors of the described paper) most people just take pieces of leaves, illuminate them directly in the tank and present ridiculously low PAR values for this particular plant, because it is grown ALONE in direct light. Their goal is to publish and receive grant money. Our goal is to grow beauty, we have tanks filled with a variety plants, ALL those plants absorb something and shade each other. So, here I am trying to find a way to calculate practical values ON THE SURFACE of a REAL planted aquariums for everyone to use, and from DutchMuch data it seems that we will be able to do it!

You see, there are often people here asking what lighting they should get for their new tank. They may be not ready to invest in a PAR meter. All they know are their tank dimensions and electrical wattage of the fixtures they think of buying. Simple arithmetic calculations here may give them a way to find out for themselves, depending on the lighting type they want and the plants they want to grow.

If DutchMuch lists the plants that are reliably happy, and if people working on the Plant Finder will be willing to participate, they may already be able to put the optimal PRACTICAL values for a PLANTED TANK for DutchMuch's plants in W/gallons of electricity and W/gallon of PAR (for the beginners), and in μmol/(sec m2) (PAR) for crazy people like us.

I wish more people posted their data here for the same or different plants...

I am very grateful for the Plant Finder existence, use it a lot, but at the moment it says: "A. gracilis is a moderately demanding plant which will not show its full potential unless its requirements are met. Lighting should be moderate to intense (2-3wpg or more)..." We need to know 2-3 W/gallon of what?

MarylandGuppy: I am truly very sorry for being rude to you. My tap water is GH2 and acidic, so, naturally, I try to grow hight-light plants. I am suffering with the "dark room" tank for several years, changed substrates, fertilization, fish, plants to no success. I live in a desert, adding huge excesses of nutrients and freuent water changes are not an option. I felt very stupid when read that growing is easy. Initially, I did not even realize that it was a blanked signature statement, I thought it directed at myself. I did not understand that you statement is meant to encourage other people to grow. Also, I understand that you are protective of the forum and had the perfect right to ask if I (a newcomer) am driven by commercial interests, but I felt hurt.

Please, forgive me! You are an expert, with your help and data we may be able to find optimal light values for the plants types you grow.

Wow, I have just noticed your answered! Thank you. I think the text above addresses some of your concerns.
 

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Just to "brain storm" a bit: We really need to figure out a way to characterize lighting as high, low, etc., taking into consideration that light from any kind of fixture drops in intensity with distance. For typical fluorescent lights it drops approximately proportional to one over the square of the distance from the bulb/reflector. For typical long LED light fixtures, with lots of LEDs strung out in rows, and with typical 120 degree optics from the clear plastic protective "cap" over the junctions, the drop in intensity is closer to being proportional to one over the distance (not squared). This means a 20 gallon tank with the light fixture sitting on top of the tank, has a much lower light intensity at the substrate surface for a 20 gallon tall tank vs a 20 gallon long tank for the same fixture. I think the ideal light fixture is suspended about as far above the top of the tank as the tank is tall. That reduces the variation in intensity in the tank. All of this makes it very hard to say that an X wattage light gives you Y intensity for a 20 gallon tank. When I went through a less complicated study of this I decided I would have to use the intensity at the substrate level as the parameter for determining what is high vs. low light intensity. I have been hoping for several years now that someone like you would do some more serious thinking about this subject, than I was able to do.

I try to avoid sending people to other forums, but this is as far as I was able to go on this subject: http://www.plantedtank.net/forums/10-lighting/184368-lighting-aquarium-par-instead-watts.html
 

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Discussion Starter · #18 ·
MarylandGuppy: Yes, this is a very a tall order. But if we manage to get people here to participate with practical data, it is possible to find out what PAR values are optimal for different plants set-ups. Then people will be able to better use manufacturer's PAR data, people here would have a better idea about the PAR they actually need.

Wattage is relative to PAR data, but agreed, we must take into consideration the angle of LED lenses. I bought 45 degrees lenses, have not received them yet. I will test them and post the results and drawings, if I can only figure our how to post the drawings :rolleyes:.

Agreed that the dimming capabilities will alter light output. At the moment I am thinking of making 200W fixture with dimming, set it over the tank and experiment with outputs, then post here tank photos and PAR data (PAR and spectra)

Thank you for the rest of the advice! I will use it!
 

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Discussion Starter · #19 ·
Hoppy: thank you! Wonderful post! We will do it together! Please give me time to carefully read it, think about it, so I could try to give an intelligent input. Work tomorrow...
 

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Wow, thank you! It is becoming useful!

MarylandGuppy: I am truly very sorry for being rude to you. My tap water is GH2 and acidic, so, naturally, I try to grow hight-light plants.

Also, I understand that you are protective of the forum and had the perfect right to ask if I (a newcomer) am driven by commercial interests, but I felt hurt.

Please, forgive me! You are an expert, with your help and data we may be able to find optimal light values for the plants types you grow.

Wow, I have just noticed your answered! Thank you. I think the text above addresses some of your concerns.
No one can be rude to me, I'm over fifty and grey!:D

Commercial interests, hurt? Come on now.
It's not even being protective even.
Every once in a while someone "feels" the forums for lighting ideas.
They talk big like they will build an ideal light fixture and sell it to everyone.
After 6 posts or so they are never seen again.

No expert either, far from it.
Still don't have a Dutch tank setup because I'm still playing with so many plant species.

Regarding ideal PAR for a species.
This is tough the way we plant in a tank.
Say we have 100 PAR (at substrate, typically measured here) and 15 species of plants.
They are all performing well, it is hard to say which ones would be sustainable in lower PAR.
Where would you put them to test a lower PAR level? Another tank? How many tanks?
Dim the entire tank some and risk some species suffering?
Many people would need to report their findings and have PAR meter accessibility.
 
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