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The high light requirement myth

Discussion in 'Lighting' started by Gerryd, Jul 18, 2010.

  1. csmith

    csmith Guest

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    barbarossa4122,

    We have relatively similar setups. I have a 55 gallon with 2x54w T5HO 13-14" above tank and a 20 gallon tall with 2x24w T5HO 12-ish" above the tank. I've just now got the algae on my 20 gallon under control (aside from the GSA), but I'm starting to think even 12" above the tank is a little too much.
     
  2. barbarossa4122

    barbarossa4122 Guru Class Expert

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    Hi csmith,

    When you say a little too much...........do you mean a little much too high or a little too much light ?
    Right now my lights are about 29" from the substrate (60 par) and my wife said she's going to "kill" me b/c she thinks we do not have enough light anymore. I am going to be "killed" if my/her plants are not going to grow and look healthy. :)
     
  3. csmith

    csmith Guest

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    Too much as in a little more light than I need. I'm sure it's a ton better than when I had the lights sitting directly on top of the tank, though, so I should probably be happy with what I have now.
     
  4. barbarossa4122

    barbarossa4122 Guru Class Expert

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    OK.:) Viva low light !
     
  5. Ralleh

    Ralleh Junior Poster

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    I have a 10 gallon tank with 3 f17t8/65s right over the water level, would you guys recommend that I turn one of them off?

    5.1 wpg sounds like too much, but maybe it's different with a 10 gallon?

    I just decreased the photoperiod from 10 to 9 hours...is that a standard amount?

    I don't currently have any algae problems, except for the type that grows on the glass, but I just clean it off the front pane and let the snails eat it off the others.

    I have DIY co2 feeding through one of those porcelain/glass diffusers into a homemade reactor and I'm using the EI method.

    Any thoughts are appreciated.

    edit: This seems to indicate that I might be OK with all 3 on:

    [​IMG]

    Due to the relatively low output of T8s.
     
    #45 Ralleh, Sep 12, 2010
    Last edited by a moderator: Sep 12, 2010
  6. Gerryd

    Gerryd Plant Guru Team
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    Hi,


    If all seems fine, leave it alone.

    But, 3 lamps for a 10 gal sounds like overkill esp with diy c02. WPG is pretty meaningless but for a 10 gal it can be useful perhaps :)

    Any graph that does not include PAR values is unfortunately not going to give us an idea of the amount of usable light the plants receive..

    Hope this helps.
     
  7. csmith

    csmith Guest

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  8. jonny_ftm

    jonny_ftm Guru Class Expert

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    Even if you didn't have algae (but you have on glass as you say...), I don't see why you run with 5wpg when 1-2 wpg can achieve same results (in fact, even better results), unless your goal is a super fast growth for some monthly aquascaping competition...

    Your energy bill will be much lighter withh less light, your plants will surely do better

    In my signature, my 12gal is running since quiet one year now with 0.9wpg, 8h/day... and not with only "low light plants"
     
  9. Sherwin

    Sherwin Junior Poster

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    Hi All,

    My first time post here, however I've been lurking in this forum since 3 months ago since I found this wonderful forum. This forum has made me decided to take the low light with Co2 path in the last 1 month and I'm happy with the result. I took many of you guys here advices from various therad, eventhough it stir my head upside down very hard to just believe of what you guys talking at that time compare to what I've read a lot in other forum or books, but now I'm a believer with the result. So I'm thank you to all of you for this wonderful forum.

    Btw regard to the low light, what do you think on 40 G tank, 18 inches height, currently I put 3 bulb of 21 watts NO T5 at 8 inches from water surface? is it too much? so far in the last 1 month, the algae issue has reduce a lot especially the BBA, totally gone. Now I still have GSA and something on the glass that can be removed very easy but the GSA is also reduced but slow.

    I still have my homeworks on my CO2, nutrient and flow though that might be the reason for the GSA, but just wondering if it also contributed by too much light. Now I need to do the homework one by one :).

    Thanks guys.

    Regards,
    Sherwin
     
  10. shoggoth43

    shoggoth43 Lifetime Charter Member
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    You may need to tweak this up or down somewhat. I ran with two T5 NO lights at 32W each on a 40 gallon breeder and did fairly well with it despite the overhang on the ends.

    You have quite a bit more light than I did since your bulbs actually fit the length of the tank, and you're a bit closer to the surface than I was. However, based on Hoppy's graph you're pretty much where you want to be. http://www.plantedtank.net/forums/lighting/105774-par-vs-distance-t5-t12-pc.html

    How flexible is your lighting rig? Can you run on two bulbs or raise the level of the bulbs if need be?

    If all you have is GSA then you're in a good place. Up the phosphate does a bit and that should go away as well. ( Gerry or Biollante can probably correct me on that if I got that wrong - I'm dealing with some wierdness at work so I can't guarantee I got that one right ) :)

    -
    S
     
  11. Ratfish

    Ratfish Junior Poster

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    Well, according to that chart, it would seem that 1 PC bulb is roughly equivalent in intensity to two of my T8s, so I could achieve your results if I turned one off. The problem is that the tank doesn't look as good to me. Granted, I'm not always looking at it, so I could just turn on the third light when I am.

    Is the contention that there will actually be more growth with less light or just the same growth and less algae with less light?

    I just completely rescaped by tank and am trying to get it to grow back in as fast as possible. Once I get to where I want to be, I'm going to scale it back. If it will grow faster with 2 T8s vs. 3, I'll definitely do that. As far as my DIY CO2 goes, it must be sufficient since the plants are pearling like mad and the tank looks like a champagne glass.
     
  12. Sherwin

    Sherwin Junior Poster

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    Hi, thanks for the replies. Yup, all I have now is GSA and a bit of diatoms on the right part of the tank where I put my Co2 injection on the left. That is why I'm thinking of the CO2 and flow issue. In the past diatoms and BBA are much severe when I'm still not using CO2 or using CO2 but with bad diffuser, it makes even worse. Now I use a reaktor so I'm thinking of put additional flow to see if it will improve the situation.

    Not wrong regarding the phosphate, I remember read somewhere regarding to it in this forum, but now I haven't use EI yet and still using pre-made fert. Then I might try to increase the macro's ferts a bit and see how it goes.

    Regarding the light, I've seen Hoppy's chart in the past before I replaced my previous one, but if I recall correctly, it has T5 HO there and not the NO. Maybe I need to check again, as long as the light is on the low light area, I can stop thinking of the light and focus on CO2 flow and ferts.... My light fixture is flexible as I can turn on 1,2 or 3 bulb if required. currently I use 6500K for all of 3.
     
    #52 Sherwin, Sep 14, 2010
    Last edited by a moderator: Sep 14, 2010
  13. shoggoth43

    shoggoth43 Lifetime Charter Member
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    If he's got the T8 curve I'd probably use that one. It won't be entirely accurate, but should at least get you within an order of magnitude.

    -
    S
     
  14. jonny_ftm

    jonny_ftm Guru Class Expert

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    What ever is your lighting, if you adjust CO2 and nutrients + keep on 50% weekly WC, algae won't be an issue. If you follow EI, only CO2 remains a culprit

    Now, about your question, with T5 light, I think you can't say it is a low light setup, especially with T5 bulbs

    With lower light, it is easier to tweak CO2. The higher the light, the more is CO2 demand. GSA can also be a CO2 issue. I tested it many times in my tanks. In tanks with high light and a fertilized water (like with EI), lowering CO2 will induce GSA, you can try it once you have a balanced EI tank

    I'm a complete believer in Tom CO2 "theory" or "evidence" I should say. Nutrients are less of an issue in high CO2 light limited tanks
     
    #54 jonny_ftm, Sep 21, 2010
    Last edited by a moderator: Sep 21, 2010
  15. SuperColey1

    SuperColey1 Guru Class Expert

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    T5 NO will be not too far from T8NO. Pretty much the same wattage for the same length. the diameter of the tube won't be a huge difference.

    The reason that T5HO is so much of a difference is that they are blasting more light out of the same small area. That means more intensity and more penetration. The T5NO/T8NO will be not that far apart.

    AC
     
  16. Sherwin

    Sherwin Junior Poster

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    Hi Jonny,

    Yup, I'm agree on the CO2 and nutrient theory. It just I don't have light meter hence I don't know whether my light is low enough or not. If it is still in the medium light, then I need to reduce it again. How much wattage of T5NO do you think required to get to low light level?

    I'm a novice therefore I want something easier to control, therefore I'm asking the question since light is the easiest factor. If I need to reduce to let say 2 bulb only, then I'll try it and see what the outcome.

    Thank You

    Regards,
    Sherwin
     
  17. SuperColey1

    SuperColey1 Guru Class Expert

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    For T5NO and T8 2 tubes the full length of the tank IMO is nearing medium levels. Raise them up 6" above the water and you are in the low area.

    AC
     
  18. dantra

    dantra Lifetime Charter Member
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    Gerryd, Its great that you shared your results, thanks. I am in the process of building my stand for the 45c I pick up for $100 bucks. (approx. 18"x18"x18") I'm thinking about picking up a used ADA Solar I MH-150w but I know it will be too much light unless I raise it up significantly.

    Your post is making me rethink the light purchase. I am now considering the fishneedit MH-70w although I don't have any experience with the lighting or the company. Any info will be appreciated.

    I HAVE been an advocate for lower lighting for quite some time now as can be seen in this thread on 4/29/10 post #13 and #20

    I so want to use a par meter to set up my new tank as to avoid any guess work with the lighting. You have inspired me!

    Dan
     
  19. Sherwin

    Sherwin Junior Poster

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    Hi,

    Thanks for the reply... Ah I see so I need 2 tube full length only... meaning now time to turn off 1 of my tube.... I have it about 20cm above the water currently. So I guess it is good :)

    Thanks guys...... Let see how it goes. The myth is strong here hence many recommend me to get another 2 tube on top of 3 I have now to grow plant so let see if I can broke the myth here as well :) and morover... saving my eletricity bill :)
     
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