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Rating: 3 votes, 5.00 average.

Algae Scrubber Basics 11 of 14

Posted 02/19/2012 at 09:35 AM by Floyd R Turbo




Again, patch growth, but only green.

[b]Buy or DIY?[/b]

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.

[b]3W versus 1W[/b]

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 [i]more lumens[/i] 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…

[b]Other thoughts on LEDs[/b]

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. [b]Do not use these[/b]. 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 [b]nothing[/b] 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 [i]different type of light source[/i] and isn’t UV based and shifted with phosphors. [b]Any LED lamp/bulb/floodlight/etc you can buy in a store that is not specifically a grow lamp is completely useless[/b]
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