stardustsailor
Well-Known Member
- Some reefkeepers reported that an excess of deep-red radiation provoked algae growth in the tank.
On April 7, 2013 we presented an improved version of the assembly, which we call Rev. 2.1. In this revision one of the cool-white LEDs was replaced by neutral-white, and the deep-red (660nm) LED was replaced with normal red (620-630nm) Philips Luxeon LXM2-PD01-0050. This mostly resolved the problem of better representation of warm colors. To our amazement, it turned out that this orange and red spectrum added significantly to the beauty of a reef tank. This spectrum has been mostly neglected so far, and requires additional attention.
We would like to make some notes about the algae bloom concerns. Many hobbyists believe that, due to high photosynthetic activity, the presence of wavelengths longer than 620nm may facilitate to algae growth, and therefore any radiation in this range should be eliminated from the fixture. This approach will, unfortunately, deprive us from enjoying the beautiful shades of non-fluorescent orange and red color present in many corals and fish.
The algae problem can be resolved radically by maintaining good water parameters in the tank, and particularly, by maintaining constant phosphate deficiency in the water. An American oceanographer Alfred C. Redfield discovered in 1934 an empirical stoichiometric ratio of carbon, nitrogen, and phosphorus present in marine phytoplankton. It later turned out that most living organisms require these nutrients in roughly the same proportion.
However, corals are better suited to live in the conditions of phosphorus deficiency and are capable of consuming phosphorus even when it is present in minute amounts (moreover, corals obtain a significant part of required phosphorus through food, rather than in the form of dissolved in water phosphate). Lower algae require more phosphorus for growth and cannot thrive when it is lacking. Thus, by maintaining a very low phosphate (typically below 0.03ppm) and a nitrate ratio slightly exceeding the Redfield ratio over phosphate[1], i.e. in the range of 1-3ppm, algae problem in the tank can be eliminated completely.
http://www.advancedaquarist.com/201...ider&utm_medium=slider&utm_campaign=clickthru
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Correct LEd spectrum for growing Algae
By budc on 2 years ago (2012 )
I have done much research online into determining the ideal spectrum for growing algae. My goal is to custom-tune an LED fixture for maximum algae growth and maximum filtration capacity. So far, I have not been able to verify whether Algae best utilizes the Chlorophyll A or B spectrums, or a combination of both.
I build algae scrubber for freshwater and marine aquariums. The algae is grown on a vertical substrate with the system water constantly cascading over it, and illuminated on both sides. So far, the vast majority of people grow the algae with low-kelvin (2700-3500K) CFL or T5HO with great success. LED builds have been all over the board, but some evidence suggest that algae (at least, marine algae) responds best to 660nm “deep red”. Thus the limited data would seem to indicate that marine algae (green hair algae, in specific) absorbs mainly the Chlorophyll “A” specturn.
Adversely, the horticulture industry reports that plants respond much better to the equivalent wattage (input) of 630nm. Growth of plants under 630s far exceeds growth under 660s. The theoretical explanation is that 630nm LEDs output 3x the power of 660nm LEDs, and that the difference is mainly the result of intensity trumping spectrum.
The “A” finding is also compounded by the apparent total lack of algae growth under warm white LEDs supplemented with 455/460nm LEDs (“B” peak in Blue). The lack of correct red component may be partially to blame, so this is only anecdotal.
I am currently preparing to run an experiment with 2 separate fixtures, one tuned to the “A” spectrum, and another tuned to the “B” spectrum. The experiment will be performed on 2 separate uninhabited saltwater system with fertilizer mixed in the water, essentially creating waste water or runoff water.
I would greatly appreciate any insight from anyone who has attempted to grow algae using artificial LED light. I posted a similar request on Oilgae and got zippo for response.
http://www.cleantick.com/questions/q/correct-led-spectrum-for-growing-algae
....................big shocker............. NOT