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Thread: Turf scrubbers vs. other nutrient export

  1. #21

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    Re: Turf scrubbers vs. other nutrient export

    The flow across the surface of a vertical ATS is VERY fast. It is a very thinn sheet of FAST moving water. Very hard to achieve that in the water. The size of pump required to achieve that flow rate at the algae-water interface would have to be huge!

    It is my impression that my algae has very little contact with air. It is encased in the sheets of rapidly flowing water. The bubbles that appear are from photosynthesis not a direct interaction with room air. When a spot may be directly interacting with air, it's at a low flow spot and it doesn't grow well. I think as you go away from the vertical model the necessary flow is difficult to maintain and other methods, like surge, might work better.

  2. #22

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    Re: Turf scrubbers vs. other nutrient export

    Quote Originally Posted by schnitm
    The flow across the surface of a vertical ATS is VERY fast. It is a very thinn sheet of FAST moving water.
    Ok, but wasn't SM just commenting that rate of flow isn't important?

  3. #23
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    Re: Turf scrubbers vs. other nutrient export

    Some almost looks white.
    They they are not getting enough flow.

    That screen developed in a high phosphate environment and the phosphates are now very low.
    Clean it off completely then. You don't want any high-nutrient dark stuff remaining.

    However, you can certainly produce a certain amount of light energy more efficiently with LEDs
    You can experiment if you want, but don't use LED's if you need results. I know all of what you are saying, but it doesn't matter. LED's have not worked, yet, and thus cannot be recommended.

    If you were to summarize into a few bullet points the most common modes of failure, what would they be?
    Slick screen
    Not cleaning
    Weak light
    Weak flow
    Too small

    Does a certain flow rate play a role in success or failure?
    If the screen is not rough, high flow will knock algae off.

    I thought aeration was the whole reason these scrubbers were constructed the way they were (sheets suspended in mid air with a thin layer of water flowing over them, or the old surge-style where the sheet was exposed to air for several seconds/minutes at a time.)
    Nope.

    If aeration plays no role, why not just put the sheet underwater in a conventional sump and use a powerhead or natural flow through the sump to provide water movement?
    Boundary layer:
    viewtopic.php?f=9&t=286

  4. #24
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    Re: Turf scrubbers vs. other nutrient export

    Have you paged thru my build?
    viewtopic.php?f=3&t=98

    There I show two different LED panels. The first one was ineffective. The second was effective. my feeling is a little more power would have been useful but I'm not sure, as with projects like this variables are being changed a little too often.

    Certainly the photonic rate is all that the algae cares about. (And the spectrum)

    If I were to build another LED light it would certainly be HPLEDs not gum drops again. It turns out that you can get far more light out of far less expensive LEDs by using HPLEDs. You do have to deal with the spreading issue as you generally want the LEDs fairly close to the screen because who wants a 3 foot wide scrubber? Application of some clear diamond diffuser plate would probably be desirable.


    As for aeration it seems that it is unimportant. The hair algae is the type that grows underwater. It extracts and respires into water. Exposing it to the air does not do anything to help it in that regard. If you are talking about 'classic turf' found beach side, then that is less clear. If you are using a bucket dumping style TS and you are cultivating that kind of turf, then perhaps air contact would be desirable. I will say that 'classic' turf I've grown did very well continuously submerged.

    I suspect that air contact still has minimal or no effect with a flood/drain system. The real benefit of a the F/D system is the defeat of boundary conditions. Water jetting past a mat of HA down the front of a screen results in virtually no flow right up against the algae. So under a few layers almost nothing is happening. With a F/D there is much more new water contact with all of the turf because all they water drains off then is replaced cyclically.

    Of course F/D results in discontinuous clank, woosh, clank woosh, noises which may be an issue with 95% of the setups.

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