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  • Lighting Experiment

    After reading into aquatic plant photosynthesis some I decided to try something with my lighting. I removed my ZooMed ultra sun bulb and replaced it with a AquaticLife 420/460 nm bulb I had. This bulb should cover the peaks at 430 nm wavelength for chlorophyll a and 453 nm wavelength for chlorophyll b better than the ZooMed bulb. The remaining ZooMed bulb should cover the 662 nm wavelength for A and 642 nm wavelength for B, and it will also cover anything needed in between which is not nearly as much. With this I threw any aesthetics out the window since my tank looks purple now. I don't know how well this will work, but I want to see what the effect of the light change will be on the growth, color, and shape of the leaves.

    The start
    - 8 hour photoperiod
    - plants arranged based on their lighting needs
    - no changes in CO2, ferts, or temperature during the week
    - 50% water change was done today to run the experiment on my EI dosing schedule
    - The light is placed in the center of the tank 3" above the surface of the water, and 17" away from the substrate.

    Some pictures from today









    Bulb spectrum pictures

    The top box is the ultra sun that I removed, and the bottom box is the remaining flora sun bulb. Along the X-axis the numbers read as 250, 350, 450, 550, 650, and 750. From zero, the Y-axis increases by tenths.


    Here's the link to the image for the spectral graph of the AquaticLife 420/460 nm bulb.
    http://www.aquaticlife.com/sites/defaul ... 1311207596

    I will run this for a week and post new pictures next friday. If I notice any major problems with the plants or algae I will end this experiment and swap the bulbs. Otherwise, if there is a difference I will continue to run this for a few weeks. I believe that there will be an increase in the rate of growth, but I do not think there will be any difference in colors or the leaves. If there is anything anyone would like me to watch for or anything else let me know. This is just for fun, and something different to try out even though others have tried this in a similar manner.

  • #2
    Re: Lighting Experiment

    Interesting, looking forward to seeing the results of the test.

    BTW do you have a control plant in another tank somewhere that we could judge with?
    -Jim-

    Originally posted by Albert Einstein
    If the facts dont fit the theory, change the facts
    Originally posted by Theodore Geisel
    Be who you are and say what you feel because those who mind donít matter and those who matter donít mind.

    Comment


    • #3
      Re: Lighting Experiment

      I can't believe I forgot to have a control , thanks for reminding me of that. It wouldn't be much of an experiment without one. So, I pulled one of the stems of mermaid weed and placed it in the refugium since it is only 6" deep. That way I can get similar lighting levels with the CFL bulb. The refugium is not currently hooked up to the tank, but if I get my acrylic cement today I may have it hooked up tomorrow. That way everything will be similar other than the lighting.

      The mermaid weed has proven over the past couple weeks that it has adapted to the tank (other than shedding all of its oldest, possibly emersed,leaves) by growing 5-6 new leaves on each plant. I may pull another one to have a bit more to compare to.

      Comment


      • #4
        More in the control is always a good thing!

        and remember, Document, document document and document, and when in doubt document.
        -Jim-

        Originally posted by Albert Einstein
        If the facts dont fit the theory, change the facts
        Originally posted by Theodore Geisel
        Be who you are and say what you feel because those who mind donít matter and those who matter donít mind.

        Comment


        • #5
          I did pull a few more stems and place them in the refugium, but I ran into some problems. Since the tank is still new and settling in I should have let the plants get well established before trying this, so I will be re-addressing this in the future. Right now there is not enough evidence for or against this lighting change. The rotala macrandra 'green' and 'variegated' both grew very well without any problems. Although, the mermaid weed started loosing leaves quickly. The problem there is I had to trim the rooted stems because all the lower leaves had been lost before this, so I believe this is just a continuing problem. The control mermaid weed in the refugium is doing the same thing. There was a floating stem of rotala rotundifolia that I moved to the refugium also, and it and the rooted portions in the display are both doing just fine.

          Once I have a good running record of this tank between pictures and the written notes I will try again, that way I will have a lot more to compare to. I was just worried about losing my plants.

          Comment


          • #6
            keep them running and see what happens, its still able to give resutls
            -Jim-

            Originally posted by Albert Einstein
            If the facts dont fit the theory, change the facts
            Originally posted by Theodore Geisel
            Be who you are and say what you feel because those who mind donít matter and those who matter donít mind.

            Comment


            • #7
              Be careful of algae. You are playing with the actinic range of lighting that is used solely to grow algae. Plants cannot utilize with wavelength.
              - Dena

              All our dreams can come true if we have the courage to pursue them.
              Walt Disney

              The only true wisdom is in knowing you know nothing.
              Socrates

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              • #8
                The bulb is swapped for now till I feel comfortable to try this again. By then I will have a better knowledge of this as I research it more.

                Based on the graphs for photosynthesis in plants, in this case chlorophyll A and B, chlorophyll A absorbs a significant amount of light in the 400-450 nm range with the highest peak around 430 nm. Same goes for chlorophyll B with the highest peak just before 500 nm. Both utilize light between the 600-700 nm range, but not as much. Carotenoids also utilize the low end of the visible color spectrum, and it doesn't use anything past roughly 530 nm. I don't really know how much of a role carotenoids play in aquatic plant photosynthesis though. Since a lot of them grow both submerged and emersed I believe it would be similar to terrestrial plants.

                With all of that I did realize algae grows well with this light too. The only thought I have on that is algae grows within the same conditions as the aquatic plants and are adapted to the same available light. If a plant is deeper underwater it is more likely to absorb light from the blue wavelength range since it is better at penetrating into deeper water. So, that is my basic train of thought on this, and would find it interesting to be able to discuss it till I try this experiment again. During the next semester I am going to pick the minds of my bio instructors that have been giving me ideas of things to try out.

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