Please note: This is the version that was posted online in early 2012.
The original LED Portion of these guidelines contains aspects that are particularly outdated. Before buying or building an LED fixture, please post a link to the fixture or post your idea in the Discussion tab area, or start a build thread in the main forum area. I have just recently re-organized the Basics into the Resources section and will be updating this section as soon as I can.
I've been meaning to update this for quite a long time, if you have any questions, you can click the Discussion tab and ask!
First: My MOST CURRENT recommendations for LED fixtures.
*** This is current as of 2015-05-15! ***
Here is my recommendation for LED lighting of a waterfall algae scrubber screen:
This is for a double-sided screen using Philips Luxeon ES 3W Deep Red 660nm LEDs without lenses (120-140 degree) running at 700mA at 2-3" from the screen to LED
Minimum coverage: One LED on each side of every 8 sq in of screen
Maximum coverage: One LED on each side of every 4 sq in of screen
Simple as that. For new screens (bare) if using the "Maximum" level, run at 350mA until mature, or use a diffuser. Might have to do this with the Minimum level also actually, but not typically. The minimum could probably be stretched to a larger area but screen will cure slower and generally have less capacity.
So for a 6x6 screen, which is 36 sq in, /8 = 4.5 per side. Make it 5.
So for a 6x6 screen, which is 36 sq in, /4 = 9 per side.
Supplementing with blue/violet: Always run blues at 350mA, violets can be run higher but should follow the same rule for the maturing stage (350 at first, then increase after maturing). Use one to two at this current level for every 5-6 reds, roughly. Lots of flexibility here, a little blue/violet goes a long way. I've used 440-445nm Royal Blue Luxeon ESs for this, but I know of at least one other that used to use RBs and switched to Deep Violets and almost doubled growth. Steve's LEDs now carries a good Hyper Violet made by SemiLED.
Regarding non DIY-LEDs in general, this is what I have roughed out to help with this.
The issue is that my DIY LED guideline is based on coverage. You can't say "I need 5 3W LEDs which is 15W, so a 15 W fixture is what I need". It doesn't work that way.
That's because a 3W LED does not necessarily consume 3W, and a purchased LED may rate it's intensity based on actual wattage used, or it may add up the LEDs and give a wattage but the actual watt draw is less. You have to watch for this.
A 3W Philips Luxeon ES 660nm LED will typically drop 2.2v across the LED at 700mA. Power = Amps * Volts so 2.2 V * 0.700 A = 1.54W. What? I thought it was a 3W. It is. That is something called MARKETING. LEDs have become more efficient over time as they have been redesigned, so a lower Vdrop and Idrive results in the same output, but instead of calling it a 1.5W and confusing everyone, they call it a 3W still.
So now on to your fixture you are looking at.
Converting the "LED per unit area guideline" to a "wattage" guideline is as simple as doing the math.
Figure out what you need per the "unit area" guideline. In the above example, 6x6 screen, minimum level (low intensity), 5x 3W per side. Each is actually drawing 1.5W, so 5x1.5 = 7.5W. Your light fixture should actually consume, at the wall, a minimum of 7.5W. The electronics built into the fixture will draw power also, meaning that you might want to add a little cushion to the number. So a 10W fixture on a 6x6 screen would be about right for a comparable replacement to an array of 5x 3W LEDs.
Now let's add that factor in and parallel it to screen size. A 6x6 screen = 36 sq in. Make it 40. you need a 10W actual-draw LED fixture on each side of this. So you could say that the rule of thumb for a pre-built LED fixture is that you need 0.25W per square inch of screen. That would get you into the Minimum light arena - or "Minimum Intensity", and you need one of these on each side of the screen.
Doubling that would put you on the higher end. 0.5W per square inch - actual wattage draw of fixture.
What you have to watch for is when they use a multi-chip that has 9 1W LEDs on it and they call that 10W. Not necessarily true. But 1W LEDs are actually more efficient than 3W LEDs when you are talking radiant flux output per unit of energy input into the LED, so it's not horrible, just shoot for the higher light level and you'll be OK usually. At best, you will actually be at the minimum level. At worst, you'll be on the low side but still OK.
Now...with that being said, here is the summary as posted in early 2012
LEDs – Why they are different
LEDs are a completely different source of light. Fluorescent, metal halide, HPS, and other HID lighting are all mercury based, and the light is shifted from the ultraviolet range into the visible range with phosphors. LEDs emit certain colors of light depending on the compounds used in the diode itself, so it is initially visible light; phosphors are then sometimes used to shift wavelength to achieve various colors.
LEDs, very recently, have proven to be highly efficient, and as more people build LED Algae Scrubbers, more information is being confirmed. There are still a few unanswered questions, but LED Algae Scrubbers so far have been shown to have a few major advantages over CFL and T5HO.
The most obvious one is lamp life - they never actually burn out (unless you drive them too hard). LEDs have what is called an L70 (or L80) rating, which is the number of hours, running at rated junction temperature, at which the total lumen output will have dropped to 70% of its original output. At this point in time, that is usually about 50,000 hours. If they are on 18 hours/day, that's about 7.6 years to L70.
However, as has been predicted, there is a big difference with LEDs when it comes to Algae Scrubbers. Since LED Algae Scrubbers ‘waste’ very little (if any) bandwidth, they are, in effect, double or better the intensity of CFL or T5HO for comparable PAR output. What this means is that you generally only need to run them half as long, or 9 hours a day (just like the double-light CFL/T5HO Algae Scrubber). Couple that with the fact that the intensity of a well built LED Algae Scrubber fixture is, on average, 1.5x the PAR of a comparable T5HO fixture (I have verified this on a Nova 1126/7 vs 50W e-Shine), LEDs are somewhere between 3 and 5 times as effective. Some DIY LED users have claimed that they have found that you can get away with 1/5 the total LEDs wattage vs. CFL or T5HO and get better results. Not only that, 50,000 hours at 9 hours/day is over 15 years to the L70 date. Some manufacturers are claiming L70 dates into the 100,000 hour range, and while that may not be proven, it’s actually highly probable the LEDs themselves will last that long (the rest of the fixture? I doubt it.)
Some possible negative factors for LEDs are the up-front initial cost, long-term phase shift, and the effect of steadily decreasing output. Phase shift is the reason that most small municipal airports are avoiding LED lighting; white LEDs are actually blue with phosphors added, and they ‘fade’ over time, and shift to blue. Runway lights are white, taxiway lights are blue, and getting them confused is bad. The LED industry is rapidly evolving, so the L70 numbers will continue to increase, cost will decrease, and issues like phase shifting will likely be improved upon. The flipside to the L70 and phase shift issues is that most people who are DIYing LED Algae Scrubber lighting will likely replace their fixture with the next best thing before this ever becomes an issue, if it even becomes an issue at all. With a stock fixture, at least those currently available at an affordable price, will probably fail for some other issue before the LEDs go bad (driver, power supply, fan, moisture problem, etc), prompting the user to replace the fixture with a better one.
LED Grow Lights for Algae Scrubbers
The LEDs that you want to use for growing algae on an Algae Scrubber are the exact fixtures that are used to grow plants. There are different plant-growth fixtures available, and some are not what you want. ‘Flowering’ lamps have a lot of variety of lamp types that you do not need.
Note: Unless your LEDs require heat sinks, they generally are not powerful enough to grow thick algae. Stay away from any fixture that has low-power LEDs, such as a fixture that has 250+ LEDs, but only required 15-20W of input power (20W / 250 = 0.08 W/LED = useless)
Here’s the bottom line: you only need RED. Nothing else is really necessary. White LEDs of any kind have not proven to be highly effective, and neither are Blues (with the exception that they accompany reds in a low ratio).
The best results so far have utilized 660nm “Deep Red” LEDs; there have been far fewer attempts using 630nm Red LEDs. These wavelengths roughly correspond with the Chlorophyll A and B red peaks. Optionally, some 455nm Royal Blue LEDs can be thrown in; according to horticulturalists, and one study by NASA, this ratio is approximately 7:1 red: blue.
One Algae Scrubber user, who has made multiple LED Algae Scrubbers over the past couple years, commented that the use of only 660nm produced great growth, but with the addition of a single blue LED, that growth got ‘stronger’. The algae was more difficult to scrape from the screen, and the strands were more stringy or ribbon-like, and less hair-like. This anecdotal evidence suggests that the blue component is used supplementally in some fashion. So a little blue can’t hurt; add too many and you’re probably just wasting power.
To my knowledge, no one has tried 660s in combination with 435s (which are the corresponding “A” peaks) or 630s with 455s (“B” peaks); however I have a couple of fixtures that I had custom made just for the purpose of testing this. Eventually. Sigh.
Recently, someone told me chlorophyll utilizes the “A” band during midday sunlight, while the “B” band is utilized more in the morning and evening, when the “A” band is mostly reflected and/or absorbed by earth’s atmosphere. Anecdotal evidence seems to support this.
Here are some examples of LED fixtures people have made, and a few growth pics as well.
^^ That was how it looked at first, and below is how it looks more recently (9 days growth)
He stated that “due to the reduction of parameters, now my net grows quite thin, on the other hand not increased my biological load, so I assume that growth is normal”. Thin? Yes. Green? Yes. With CFL or T5HO, you would tend to get yellow growth.
^^ notice mostly shades of green. Only green.
Again, patch growth, but only green.
Buy or DIY?
There is still a relative lack of selection in stock LED fixture that are satisfactory for our purposes, and an even greater lack when you’re trying to keep the cost low. So far, the only one I have come across that is even close is the 50W 4G grow light from e-Shine systems. This is a cheap fixture from China (usually between $100-$120 each, shipped) and has little track record. And like anything you buy from China, you get what you pay for, and if something goes wrong, chances are it’s easier to throw it away and buy another than to get it repaired. It does have a pair of fans on it, which means it can suck in moisture (and it’s not wet-location rated) and people have reported fan-cooled fixtures failing or the fans getting louder and louder over time (not just e-Shine fixtures, either). But, time will tell. For now, it’s what we’ve got available.
There are LED grow bars available (from China) that don’t have fans and are supposedly waterproof, but these are relatively new, and from what I’ve heard about them, they are not reliable. Also, they are generally only available in 1W arrays, and the density of LEDs is not enough. This might change in the very near future…we’ll see.
The 50W e-Shine fixtures are a tight array of 1W LEDs – 2 rows of 25 each, about 1/2” on center, 45 660nm Deep Reds and 5 455nm Royal Blues. What’s nice about this is that you can put it right up against the Algae Scrubber enclosure, within 2” of the screen, just like a T5HO. These definitely need to have acrylic or glass between them and the screen due to vent holes for airflow, and they weigh about 9 lbs each, so properly supporting them and protecting them from moisture is key to longevity.
There is a decent mathematical reasoning for going LED.
For initial cost, CFL and dome reflectors are the cheapest; clip-on dome reflectors are $10 or so each. Replacing lamps might run you as low as $10/year for a small Algae Scrubber, and as much as $30-$40 or more a year for a larger Algae Scrubber. CFL is the best low-cost alternative for the ‘cheap and easy’ build.
T5HO is more, either a stock fixture or end caps and reflectors, so your initial investment can be anywhere from $150-$220, then lamps are running currently about $5 each, and you need to replace those every 3 months or so (depending on the “on” time per day). If you have extra T5HO parts or fixtures laying around, then you could go with that. But setting aside the moisture concerns, going out and buying new for an Algae Scrubber has, IMHO, progressed past the point of diminishing returns.
Buying a pair of stock LED fixtures is going to run you $200 minimum, and could last years. Compare an Algae Scrubber using the 50W e-Shine 4G Grow bars to one using 2-lamp T5HO fixtures. Initial cost of 2 T5HO fixtures and 4 grow lamps will run you around $170-$220, and a pair of the e-shine fixtures about $220 (ballpark). T5HO lamps every 3 months will run you $20, or $80 per year. The e-Shine fixture break-even point is, at worst, just over 6 months. In the first 3 years, you can buy a pair of e-Shine fixtures for each T5HO fixture and break even. Just based on lamp replacement cost alone, the e-shine fixture only has to last 2.5 years to break even. It’s likely that a better product will be available within that time frame.
DIYing an LED array for a small Algae Scrubber might run you less than $100 and could last years as well. For the DIYer, there is a product that you can spray onto your fixture that makes it essentially waterproof. I personally don’t know much about this product but I have heard it works very well. If you feel up to building your own LED Algae Scrubber, at this point, I say knock yourself out. Just make sure you do your homework before putting pen to paper; study other designs and learn from the mistakes and successes of others.
As far as active cooling, for either a stock or DIY fixture, it would be ideal if the source of airflow to the LED fixture’s heatsink came from outside the sump or tank area. Not easy to do, and this is one inherent downfall of the LED Algae Scrubber.
3W versus 1W
With an Algae Scrubber, the goal is even coverage. CFLs have a bit of a problem in this regard, unless you use a good reflector. T5HO has few issues due to the linear nature. LEDs have an inherent issue with spotting.
One thing that is important to point is that 3 x 1W chips will put out more lumens than one 3W chip. Why? Because as technology has progressed, marketing has stuck itself in the mud. A 1W chip does not pull 1W and a 3W chip does not pull 3W. Some may argue this based on measured current and voltage drop, and I don’t want to get really technical here because by the time I post this, it will have all changed again (LOL).
3W chips need to be appropriately spaced and distanced from the screen to avoid spotlighting. The distance from the screen is the biggest downfall. You can put diffusion grating in front of the LEDs to help distribute the light better, but that also tends to cut down the intensity. Not much, but we’re going for best bang for the buck here. Lenses should be completely avoided (they only make spotting and burning worse). Most DIYers prefer 3W LEDs. Just space them out so that you get as even coverage as possible. The consensus seems to be that you need 1/3 to 1/4 the total wattage of 3W chips as you would fluorescent lamps for the appropriately sized Algae Scrubber. As previously mentioned, some even claim 1/5 the wattage.
I’ve been researching a bit on how many 3W LEDs you need to use. The general consensus at this point seems to be that you need one 3W LED on each side for every 15-20 square inches of screen. Going with the new feeding-based sizing guidelines, it seems that a simple technique would be to use one 3W LED on each side for every 12 square inches. So a 2-cube/day Algae Scrubber would need 4 3W LEDs, two on each side. Distance from the screen is something that depends on some factors, such as how hard the LEDs are being driven and how long of a photoperiod is used. New ground is being broken on this almost daily, and I am in the process of gathering as much information as I can from the DIYers so that some kind of ‘standard’ can be established.
1W chips are much better, IMO, for Algae Scrubbers, because you can pack them closer together, put them closer to the screen, and get near-perfectly even coverage. This mainly applies to off-the-shelf fixtures, which usually have one circuit board and the individual LED dies are close together. It’s hard to get 3/4” spacing using 1W chips on stars. But if you have ever had the opportunity to see a 1W LED grow lamp array in person, you would agree that they are bright as #@$&*^!%. I’m talking blindingly bright, and extremely even coverage. As far as the wattage comparison for those – not sure. The “1/5” numbers came from the DIY 3W LED folks…
Other thoughts on LEDs
Previously, I wrote that you probably should not rely on an LED Algae Scrubber for total filtration, only for supplemental filtration. This is no longer the case, not by a long shot.
Unless you are short on immediate cash and not comfortable DIYing some LEDs, there’s just no reason not to do an LED Algae Scrubber, in my opinion.
It is important to note that there has been no study that I could find that indicates what exact LED spectrum is ‘perfect’ for algae growth for this specific purpose. So there is a lot of new ground being broken right now.
Just make sure you realize that:
1) LED Algae Scrubbers do not have as long of a track record. Then again, the modern Algae Scrubber has really only been around itself for about 4 years.
2) Only recently have there been builds with any sort of success. However, some of those builds have been extremely successful.
3) Fixtures themselves are still not tested for long-term stability and reliability (mostly related to moisture issues)
4) If you build one, you’re going to be on the cutting edge, which can cut both ways. Take your time and think it through well, and don’t be afraid to ask a lot of questions.
There are LED floodlights available at the local hardware stores and other Big Box stores. Do not use these. This one below is a 3000K 75W incandescent equivalent, which equates roughly to an 18W CFL:
The problem is this: when it comes to LED, you have to throw the Kelvin rating out the window. It means nothing for Algae Scrubbers, it is only good for trying to match the color rendering given by a comparable fluorescent lamp that is used in a home or office. Remember, LEDs are a different type of light source and isn’t UV based and shifted with phosphors. Any LED lamp/bulb/floodlight/etc you can buy in a store that is not specifically a grow lamp is completely useless