Led Floodlights For A Planted Tank

[alexge]

Hi,
 
Let me start by saying that I've done some research on the matter.
And I know that there are a lot of parameters.
 
Currently I have a led strip (aqualighter 2) which is rated at 22Watt, 6000K-7000K and 2160 lm.
This thing cost me 130 quid, and it is nowhere near enough for my 140 Liter / 39 Gallon tank.
 
Before I setup this tank, I had a small tank (20 Liter/4 gallon) where I used a Toshiba LED e-core, a 6500K ultra-bright 19Watt floodlight. It was way too bright, way too much light, and I was battling constant algae problems.
 
So I was wondering, instead of paying 130 quid for another aqualighter 2, or 165 for an arcadia led spotlight,
I may as well setup a pendant style frame, and use LED floodlights.
 
Nowadays they came in all wattages, colour temps, lumens and angles.
Which raises a few questions:

1. Whats the best colour temp for planted tanks? 5000K or 6000K+ ? For example, the Arcadia eco-LED spotlight is rated at 5000K (I am guessing for a reason).
2. Should I ignore wattage? If I go with the Watt per gallon rule, then I need 80 watts, which would translate to 4 * 20Watt floodlights. Obviously thats too many for a 75cm tank, the max I would imagine I could use are 3*25 Watt floodlights.
3. I've read other posts online, where people mention as a more accurate measure, lumens per gallon/litre. If so, what is a high-light lumen per gallon ratio?
4. Angles: I guess that depends on how many floodlights I'll be using, and how I want the light distributed. If I use 3 floodlights, I could have a 6500K in the middle, with a 60 degree angle, and two 5000K at the sides, with a 40 degree angle. Am I correct to assume that anything over a 60 degree angle is simply not usefull for an aquarium?

At 35 pounds a floodlight, I'd be looking at 105 pounds for 3 floodlights of 20-25 Watt at a total of 60 ~ 75 Watts, different colour temps and lumen output (I think each are around 1200-1300 lumen depending on the model, a total of 3900 lumen).
 
Is that a viable option?

 

[Byron]

1. 
   

   Whats the best colour temp for planted tanks? 5000K or 6000K+ ? For example, the Arcadia eco-LED spotlight is rated at 5000K (I am guessing for a reason).

Studies have determined that aquatic plants photosynthesized best with a Kelvin between 5000K and 7000K.  The 5000K will be "warmer" (more red, less blue) and the 7000K will be "cooler" (more blue, less red).  I like the mix of 5000K and 6500K over my dual tube tanks, but just the 6500K is fine with respect to plant response.  The warmer or cooler is largely personal preference, as it does affect how you see the colours.  The sun at mid-day falls somewhere within this range, though I've forgotten the actual number.
 

1. 
   

   Should I ignore wattage? If I go with the Watt per gallon rule, then I need 80 watts, which would translate to 4 * 20Watt floodlights. Obviously thats too many for a 75cm tank, the max I would imagine I could use are 3*25 Watt floodlights.

Wattage is merely the measurement of how much energy a bulb or tube uses to produce the light.  I cannot be used as an indicator of the light intensity (brightness), unless one is comparing identical bulbs/tubes.  For example, the basic T8 48-inch tube used to be manufactured in 40 watts, but these are now being manufactured in 32 watts, yet the intensity of light is the same (or in fact slightly more, due to better manufacturing).  The watt per gallon rule was sort of a guide when we only had one type of lighting, namely T12 fluorescent.  But with better T8, T5, CFL and LED options, this "guide" is useless.  After all, a CFL 9w bulb produces light intensity comparable to an incandescent 40 watt bulb.
 
Your other questions are beyond my scope of experience so I will leave those for others to answer.
 
Byron.

 

[StevenF]

Currently I have a led strip (aqualighter 2) which is rated at 22Watt, 6000K-7000K and 2160 lm.
This thing cost me 130 quid, and it is nowhere near enough for my 140 Liter / 39 Gallon tank.
 

 
As Byron said ignore watts.  Think Lumens (lm).  Lumens is a measure of how much light is produced.  A book  I have suggest 500 to 1000 Lumens per gallon for medium light, and 1000-1500 for bright light.  My personal opinion is that light levels should be determined by surface area of the tank rather than than gallons.  So based on my planted tank, which I would rate at medium light) that works out to about 10 lumens per square inch. Note if you don't have plants in your aquarium you can get by with a lot less.  For an unplnted tank the fish preference and your preference would be more important.  
 

floodlights, I could have a 6500K in the middle, with a 60 degree angle, and two 5000K at the sides, with a 40 degree angle. Am I correct to assume that anything over a 60 degree angle is simply not usefull for an aquarium?
 

 
Obviously the shallower the angle to greater the amount of light that is reflected.  At 90 degrees most of the light will get through. At less than 10 most will be reflected.  I am not sure what the appropriate angle is.
 

At 35 pounds a floodlight, I'd be looking at 105 pounds for 3 floodlights of 20-25 Watt at a total of 60 ~ 75 Watts, different colour temps and lumen output (I think each are around 1200-1300 lumen depending on the model, a total of 3900 lumen).
 

 
A efficient LED will produce about 90 lumens per watt (assuming a very efficient AC to DC converter in the lamp).  So 25watts should get you about 2250 (assuming a very efficient AC to DC converter in the lamp.  So I would think 3 lamps would get you about 6000 lumen.  Note that if you use dimable LEDs you could go for very high lumens and then use a dimmer to reduce the output to what you want.

 

[alexge]

Hello,
 
Thanks both for your answers.
Especially StevenF, your answer helped temendously.
I think I'll stick with colder 6000K+ I don't like the warm lights as much as I like the colder ones.
 
Regarding lumens, here's whats troubling me with the lumen/gallon ratio.
 
My tank is 39 US gallons (140 Liters), and the surface area is 75cm (29.5 inches) by 45 cm (17.7 inches).
In Lumen I would need anywhere between 19500 up to 58500 lumen, if I used the lumen/gallon ratio.
 
The PAR-38 floodlights appear to range from 600lm up to 1400lm, depending on wattage, diode quality (brand?), beam angle and Kelvin colour.
This ratio therefore makes no sense to me: for my small fish tank, I would need 19 floodlights if they average 1000lm each.
That is 285 Watt to produce the light intensity required by this ratio.
 
I honestly believe this ratio is rubbish.
The surface ratio SteveF describes makes a lot more sense:
If I go for 10 lumens per square inch, then my surface area is 522 sq. inches, thus I need around 5220 lm, which still seems a bit too much, but roughly translates to 4 LED floodlights.
 
Regarding LED lumen output, I have no knowledge other than the quoted lm output from the products.
I will argue that some brands may be more accurate (Toshiba, Philips) whereas others may inflate their output (Utilitech, Jacky, Chinese brands).
 
Toshiba E-Core 19.7 Watt (the one I currently own) with 35 beam angle, 6500K is rated at a tad over 950 lumen.
Ultilitech 23 Watt PAR 38 LED, 5000K and no mention of beam angle, rated at 1400 lumen.
JACKY 26 Watt PAR 38 LED, 5000-5500K at 60 degrees beam angle, rated at 1300 lumen.
 
3 of those would total anywhere between 3000 lumen to 4200 lumen from 60 to 78 watt.
Cost wise, that is roughly 90 GBP for 3 LED PAR 38 floodlights, in comparison to 260 GBP for 2 Aqualighter 2 rated at a total of 42 watts and claimed 4200 lumen.
If I aim for the 10lm/sq. inch ratio, I need 4 LED PAR 38: 4 * 30 = 120 GBP, whereas I would need 3 Aqualighter 2, overshoot the lm needed ( 6400 lm ) and they would cost 390 GBP.
 
What puzzles me, is how can Toshiba, Philips and other brands claim 20 Watt ~= 1000 lm, and the Ukrainian Aqualighter company claim (they use CREE LEDs) 22 Watts ~= 2160 lm.
Obviously there is something I am missing, technology wise.
 
But what is evident, is that even cheaper aquarium LEDs such as Aqualighter (I won't even go into Geisemann, Elos or Kessil LEDS) cost a fortune,
whereas an array of LED PAR 38 floodlights can achieve the same output for a fraction of the price.
 
Surely there must be something I am missing here?

 

[StevenF]

Obviously there is something I am missing, technology wise.
 

 
white LED are actually blue LEDs with a phosphor coating.  The blue light from the LED is converted to green, yellow, and red by the phosphor.   for LEDs with a color temperature  of 2700K little to no blue gets through the phosphor.   2700K Leds produce mostly red, green, and yellow (RGY).  A 5000K LED may have the same phosphor but simply less of it.  As a result there are more gaps between the phosphor particles and  more blue can get out.  So a 5000K LED produces vastly more blue, in addition to less RGY.  Additionally the phosphor is not 100% efficient some of the blue light in a 2700K LED never gets converted to ,RGY and is simply lost as heat.  The end result is that a 5000K temperature white LED may produce more lumens per watt than a typical household 3000K white LED.   
 
However allowing more blue light out does have a cost.  The blue emitted by the LED is monochromatic blue at a wavelength of 465nm.  other blue wavelengths between 400nm to 480nm are simply not there.  The phosphor in comparison can produce all light wevelengths from about  480nm (blue  down to about 640nm (red).  The sun in comparison produces light from 700nm (infrared) to about 300nm ultraviolet).  Todays LEDs cannot reproduce the full spectrum of the sun.  
 

Studies have determined that aquatic plants photosynthesized best with a Kelvin between 5000K and 7000K.  The 5000K will be "warmer" (more red, less blue) and the 7000K will be "cooler" (more blue, less red). 
 

The may be true for natural sunlight, but it is unclear to me it that holds true for LEDs  The Reduced blue spectrum of LEDs my not work as well for plants.  Incandescent in comparison does much better at reproducing the sun full spectrum.  Unfortunately Incandescent use a lot more power and don't last.  Good florescent lamps will do a much better job reproducing the full spectrum of blue, green, yellow, and red.  Florescents due a better job than LEDs due to the fact the phosphor on fluorescent lamp is converting UV into visable light.   
 
Part of the reason Kessil LEDs cost a lot more is that the light uses multiple blue LEDs to cover more of the blue specturum in addition to multiple white LEDs.  So for Kessil you are really paying more for the better spectrum.  For Geisemann, Elos, and  Kessil LEDS also have software controls that may be useful for some people, but at an additional cost.
 
 

What puzzles me, is how can Toshiba, Philips and other brands claim 20 Watt ~= 1000 lm, and the Ukrainian Aqualighter company claim (they use CREE LEDs) 22 Watts ~= 2160 lm.
 

 
Key word is Claim.  In many cases there are few law or regulations requiring that the specs listed on the box or web be accurate and few organizations and governments that verify the claims. Now people can take legal action if they feel a product doesn't live up to the claims.  However most of use don't have the equipment or knowledge to accurately check the claims.  There was one company that was taken to court by the US for fraudulent claims on the packaging.  the the government did win.   I did personally change all my bulbs at home to LEDs most are 3000k.  I have gotten good result from  fiet electric, Sylvania, and Ultratech.  I have 3 PAR38  Sylvania LEDs that consume 21 watts, 2700K, at 1150 lumens.   I have found these brands have spec labels that are more consistant with the spec labels on incandescent bulb boxes.  I use 3000K bulbs on my aquarium.

 

[alexge]

StevenF,
 
This might be far fetched, but do you think that mixing different LED floodlights might better reproduce the sun wavelength?
For example, one at 5000K, one at 6000K, one at 6500K etc.
 
Although I've seen that most manufacturers dont claim one specific temperature, but  a range (e.g., 6000K ~ 6500K).
 
Excellent post btw, really helped put things into perspective D

 

[alexge]

It seems like I was wrong in my cost calculations.
I found Belgium-branded CREE LED floodlights, at 11 GBP each, rated PAR 38, 36 Watt, 1650~1800 lumen, 60 degree beam, and available at Warm White(2700K-3300K); Cool White(6000K-6500K) ;Natural White(4000-4500K).
That is a bargain (provided they are not utter crap) since I can get 5400 lumen at the cost of 33 GBP !!!
I'm thinking of mixing Cool white (6000K-6500K) with Warm white (2700K-3300K) hoping this should give my plants (and fish) a nice range of red and blue light.

 

[StevenF]

This might be far fetched, but do you think that mixing different LED floodlights might better reproduce the sun wavelength?
For example, one at 5000K, one at 6000K, one at 6500K etc.
 

 
My guess that combination would dnot do much.   But is you have 2700K and 6000K You might get better coverage of the read spectrum.  however no combination of white LED will give you better  coverage of the blue spectrum.  
 

I found Belgium-branded CREE LED floodlights  (provided they are not utter crap)
 

 
If the entire bulb was made by Cree it is probably good.  I have never heard anything bad about there products and they make there own LEDs.  however if it has some other brand name on the box it was not made by Cree but might use Cree LEDs in the assembly.  If that is the case there is no way to know.  The good thing about using PAR38 bulbs is that if you don't like one vendor, you can try another.

 

[alexge]

No the entire thing is not made by CREE, its made by Ranpo which is a Chinese company (http/ranpolighting.com/) the retailer is in Belgium, they claim they use CREE LED's in their bulbs:
 
http/www.ebay.co.uk/itm/281795101626?_trksid=p2055119.m1438.l2649&var=580791145599&ssPageName=STRK%3AMEBIDX%3AIT
 
They do lower colour bulbs (2700K-3300K) so maybe I should mix one on the lower end and one on the higher end?
Money-wise it works out very cheap, so even if they are total crap, I could try another brand like you said.
 
On the plus side, they are dimmable, so there's that
 
PS: I went ahead and ordered one on the low end spectrum and one on the high end.

 

[StevenF]

Never heard of Ranpolighting, I hop they work out.  However I don't like the look of the heat sink.  In the picture there are slots around the leds.  These are commonly part of the heat sink.  These slots typically link to slots near the connector at the top end.  However the pictures don't show corresponding near the connector.  hot air leaves through the top and cold air is pulled in at the bottom.  Without the slots at the top the hot air would have no where to go and the bulb could overheat. I hop I am wrong or the picture is wrong.
 
But the way how are you going to mount the bulbs above the aquarium.  

 

[alexge]

You know what, that's what I was thinking, why are all other manufacturers creating them with cooling fins and such, and they don't have anything for cooling?
My guess is the actual aluminium body acts as the heat-sink.
The slots you mention may help hot air to escape, even from the wrong side of the bulb!
In any case they have a 3 year guarantee, so even if they burn out I'll try to get them replaced.
 
I'm going to mount them on a stainless steel mounting kit I got from iquatics:
http/www.iquaticsonline.co.uk/aquarium-light-mounting-kit-hanging-bracket/aquarium-light-mounting-hanging-suspension-system-600mm.html
 
Its a bit overpriced, but its really well made, and its should support up to 12kg of weight.
 
The only other thing I need is E27 pendant-fixtures, and there’s some nice fabric ones on ebay, as well as the dirty cheap silicone ones from China.

 

[StevenF]

I'm going to mount them on a stainless steel mounting kit I got from iquatics:
http/www.iquaticso...stem-600mm.html
 
Its a bit overpriced, but its really well made, and its should support up to 12kg of weight.

One idea came to mind which prompted my question  have you ever considered track lighting? Unlike the Aquaticso the track lighting gets its power through the track. If you put track lighting on the ceiling right above the aquarium, then attach pendants to the track and  position them above the aquarium..  You could also attach a short section of track to the Aquaticso  and then attach the pendants.  If you are not familiar with track lighting  I found a video that might clarify what I am talking about.  
 
https/www.youtube.com/watch?v=nqI2otyHV4k

 

[alexge]

I was googling around for the lumen/gallon ratio and any kind of info I could find on the subject,
and I came across a blog which states the same thing you told me on how to calculate lumen/square inch. (didn't save the URL)
 
The guy who owned the blog said that 10 ~ 16 lumen per square inch is a low light environment.
 
Hi Steven,
 
That is a really nice idea.
Unfortunately I am renting, so I can't be doing such modifications to the ceiling.
If I could, I would have gone for light pendants from the ceiling.
That is one of the reasons why I have a rather small aquarium (40 gallons) although at some point I'd like a much bigger one.

I got some diatom algae bloom this week, since I added an extra LED Floodlight, so I sat down and did my lumen calculations again.
 
Right now, I have the aqualighter 2 - 60 cm, which produces 2200 lumen and an extra Toshiba e-core which produces another 1000 lumen.
So I am supposed to be below the "high light" threshold of 5000 lumen needed for my aquarium's surface area, as I am getting around 3200 lumen.
 
Yet, ever since I put the toshiba e-core, I have had diatom algae bloom.
Before I added the e-core, I had minute amounts of diatoms, mostly on the moss right below the surface, which are closest to the light source.
This obviously means that this amount of light was too much for my aquarium
 
Having removed the Toshiba e-core, and using only the aqualighter, I am at less than half the ideal lumen per square inch, at 2200 lumen (instead of 5000).
The high-light plants such as Rotala Walichii are not doing OK, its obvious they need more light.
But the rest of the medium light plants (pogostemon erectus, Alternanthera Reineckii ) are absolutely fine.
The carpet is taking too long to fill in, but they are otherwise ok.
 
Which makes me think that this ratio is either biased towards low intensity leds, or should take into consideration the spread/angle of light.
For example, my aqualighter is a strip, so the 2200 lumen are spread over a large area.
The Toshiba e-core, being a floodlight/spotlight concentrates 1000 lumen in a small area, thus causing diatom algae bloom at that spot and nearby areas.
 
I think the sweet spot for my tank is somewhere between 2500 ~ 3000 lumen, and that is empirically hypothesized but not tested.
Obviously I will need the dimmers, and I may have to borrow a PAR meter, or get one of those cheap chinese lux meters, waterproof it and stick in the water.

 

[alexge]

Well, after a few weeks, and after setting this up, I have to say that the Chinese LED floodlights are disappointing.
Either they sent me the wrong wattage, or their output is greatly exaggerated.
 
At this point, I've almost spent as much as a second aqualighter array would have cost me, which is annoying me.
 
The toshiba e-core is producing more output than those Chinese leds, and its rater at half their lumen and half their wattage!
 
From the looks of it, I will need at least one more toshiba e-core (2 in total) and maybe a 3rd one, If I want to have a high light environment.
So, it may be worth just buying a second aqualighter and be done with it.