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Thread: Up-Flow ATS

  1. #1
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    Up-Flow ATS

    This idea came to fruition late last night, someone posted on my build thread on AA that since the algae grows 3D so well in an enclosed box that is flooded, why not flood the entire box? Well as I was typing and describing that if the box was full, the water would have to enter from the slot tube at the top, then exit at the top, and water would stagnate and the algae would die. Therefore, the only way to make a totally flooded box work would be to have the water enter at the bottom of the box and exit out the top, and to my knowledge this had not been attempted.

    Then it hit me - this would be the perfect design to work in combination with a tuned pipe overflow (full siphon - herbie or beananimal).

    So riddle me this - would this design be feasible?

    What I envision is something along these lines: You would have to have a watertight acrylic box with a bulkhead of some sort on the bottom of one of the sides, and this is where the full siphon would enter. Due to the high level of flow from this, there would be no slot tube to hold the screen. You could secure the screen in place by another method which I've got floating around in my head but it hasn't quite landed yet. Something to do with magnets and zip ties. The water would fill up the box from the bottom and would then have to exit out the top, either by way of another bulkhead or a spillway or sorts, or both as a failsafe to prevent clogging and overflow.

    The difficult thing to figure out will be the lighting. Obviously if you're going to all this trouble, T5HO fixtures would seem like a logical option, but care would have to be taken to not mix water and electricity because they are not happy together.

    The advantages I see are that you don't have to deal with a slot tube, spray, clogging, detaching and re-attaching the screen during cleaning, etc.

    The disadvantages are that it is not very DIY-able, there is more risk, there is not an opportunity for cooling/oxygenation since the screen is underwater, and starting the screen from scratch may involve a different process.

    But it's an idea. What do you think?

    EDIT: I did think of a flaw. Getting the siphon to start with a tuned pipe could be problematic, because the pipe would essentially be several inches underwater, making it difficult for the full siphon pipe to purge all the air. Hmmmmm...

  2. #2

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    Re: Up-Flow ATS

    I thought that the highly oxygenated environment created by the water running over the screen was an essential. Wouldn't a full siphon and a sealed box really reduce that oxygen rich environment? I could be way off and I most likely missed something, but wouldn't you get the same affect by submerging a screen vertical in your sump and lighting it from the sides?

  3. #3
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    Re: Up-Flow ATS

    Unfortunately this would make the screen submerged, which slows the flow by the boundary layer on the screen. There would probably be no growth. You could test it though, with your current unit, by just filling up the box with water after a cleaning.

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    Re: Up-Flow ATS

    What are you referring to when you say 'boundary layer'? I know I've read you using that term before but don't have the time to dig through it all.

  5. #5
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    Re: Up-Flow ATS

    What is a boundary layer, and why is it important? It the layer of water that is microscopically close to the algae; the water molecules that actually touch the algae:






    This boundary layer area of the water has zero flow, because it has to have the same flow as the algae, which of course is zero. Since there is no flow (velocity) here, nutrient transport through it is slow. The faster the water flow, the smaller the boundary layer, and the faster the nutrients can get to/from the algae from the water.

    One point to clarify about nutrient exchange: Contact with air is not needed. Scrubbers operate the same whether they are sealed or open (except for cooling/evap), because the exchange is not with the air; it's with the water. The reason algae grows better in an overflow, or where water hits a scrubber screen, or where waves hit the beach, is because the flow is higher here and thus the water's boundary layer is thinner, which allows for better nutrient transfer between the algae and the water. This is what a vertical waterfall scrubber tries to achieve: Fast flow from top to bottom. Further info can be found here:

    Seagrasses: Biology, Ecology, and Conservation, p 199, by AWD Larkum, Robert Joseph Orth, Carlos M. Duarte:

    "As water flows through seagrass [or algae] beds, a boundary layer develops on the sediment surface, as well as on each seagrass [and algae] component exposed to the moving water. The faster the water moves, the thinner the diffusive boundary layer (DBL) becomes, and consequently, the faster the transfer of molecules from the water column to the sediment and/or seagrass [or algae]. It follows then that when currents [flow] are weak, the flux of molecules to the seagrass [or algae] surface may be limited by diffusion through the [boundary layer] (i.e., physical limitation). Under those conditions, many biological sites or enzymes in the seagrass [or algae] tissue are available to assimilate molecules when/if [!] they reach the plant's [or algal] surface.

  6. #6
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    Re: Up-Flow ATS

    Gotcha. That's kind of what I thought. It sort of blow my idea out of the water (no pun intended), at least on paper. With a 1" pipe pulling a full siphon with a drop of 3 feet, the flow rate is approximately 2000 GPH or 33 GPM, 0.5 GPS. I'm guessing that's not considered to be very turbulent on this scale, the turbulence needed would have to be tantamount to a wave crash. Not looking like a great idea after all I guess. Rats.

  7. #7

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    Re: Up-Flow ATS

    If it was fully submerged, you could put a powerhead in there to increase the flow. Flow in/out of the box would be the same, but you could make the flow inside the box pretty turbulent with something like a Korilla 4 powerhead (or one at each end?).

  8. #8
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    Re: Up-Flow ATS

    yeah, or a wavemaker, if you wanted to spend $200 on one and not use it for your DT!!!

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