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Thread: Pulsed flow

  1. #1
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    Pulsed flow

    Found this, and I'm a bit concerned

    http://www.enst.umd.edu/files/KangaD...ce Article.pdf

    According to the calculations from a single sided, pulsed flow system, these regularly produce 50grammes dry weight (2.5kgs wet weight) growth per square meter per day. Have done an approximation of my growth and it works out at 500grammes wet weight per square meter per day. I think you'll agree, I've got comparatively good growth compared to others. So why is its productivity so low compared to a single side horizontal? The only difference I see is laminar flow compared to pulsed flow. Thoughts please

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    I don't think it is really even debatable comparing a surge system vs a constant laminar system. A washing machine comes to mind... take a dirty piece of clothing and hang it then dump water down it vertically, how clean is it going to get compared to putting it is a washing machine where it is agitated? If you can surge an algae bed it seems like that would be a comparable situation. It will keep the algae free from detritus and deliver nutrients much more efficiently in a surge system. Problem is designing such a system to be quiet, compact, and fail proof, all while still trying to maintain a steady water level so you can still use an auto top off system for freshwater.

    I had a new design in my head over the past week from the conversations on here for a new ATS, I was planning on starting it today... until this thread.. now my mind is racing in a different direction to try and figure out the solutions to the above problems I listed. I think the obvious answer is it would have to be done in a 3rd tank, like a separate refugium, where you can provide a surge without affecting the water level in the display or sump.

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    We will come up with some sort of test rig, I'm sure.

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    Seems like the most efficient simulation of the Hydromentia pulse flow, would be a flooding waterfall box, with an auto syphon. Bugger, I ain't got a box.

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    I toyed around with the idea of the surge scrubber a while back, my thought was to incorporate the use of a CSS (Carlson Surge System) and a waterfall scrubber, but that would require the CSS to be ancillary or very quickly filling, and then the issue is that the scrubber is only filtering when the water is surging across it.

    The other thing to consider is that the 2.5 kg/day figure is likely possible due to the presence of waste to be consumed, could be different algaes (freshwater, specifically, for wastewater treatment), plus that figure of 50-60 g/m^2/day was in June/July in California, then only 8-12 in December.

    I recall recently someone posting an extremely large waterfall scrubber that filled up with water then purged out. This is the opposite of what you would actually want, you would want the surge to flow across the screen, not to drain the now submerged screen.

    The CSS/waterfall would mean you would need a lot of space, and yes likely a separate tank, two actually. One to fill up and act as the surge source, the other for the scrubber to drain into, and you would still have level issues with the ATO.

    I think the biggest issue is that we are polishing saltwater for corals and fish to live in. Wastewater treatment plant (WWTP) scrubbers are cleaning up grey water (WWTP effluent) so that it can be purged into a river/stream and meet government guideline for safety. big, big difference

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    In the link (I think it's the one I posted) nitrate and phos levels can get down to 10 parts per billion, before limitation occurs. Been reading some stuff on this and it seems that one of the the main benefits is from the movement of the algae exposing itself to light. I'm gonna try it with an old skimmer, tiny slot tube, Perspex window frame for the screen, aerated down the screen, might be able to do double sided, auto syphon. I've got nearly all the bits so not gonna cost anything to try. The benchmark would be bettering the 0.222 g/sq inch/day im getting now. If the figures in the report are accurate, and I've interpreted it right, the screen would only need to be 1/4 of the current size, harvested every 5 days. Seems a bit too good to be true.

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    Why not just get a variable speed pump and ramp the flow up and down like a wavemaker? DC pumps would be good to use for this. Also something to consider would be a wider slot on a slot pipe that would be able to handle intermittent flow at much higher rates

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    Quote Originally Posted by Floyd R Turbo View Post
    Why not just get a variable speed pump and ramp the flow up and down like a wavemaker? DC pumps would be good to use for this. Also something to consider would be a wider slot on a slot pipe that would be able to handle intermittent flow at much higher rates
    Wider slot, yep gonna try that.

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    Floyd - you still got a UAS running ain't ya. You could try reversing the flow. The UAS is obviously uni directional, but it needn't be. You could run the water flow so the circulation rotates one way, then run vigorous bubbles intermittently to reverse the flow. Seems like it would be exactly the effect of an intermittent surge. I'm not a subscriber to the notion that the bubbles rubbing the algae is the key (the algae is never dry when a bubble rubs against it) but bubbles could be used to reverse flow. Or run two sets of bubbles on timers, sometime the flow will be up, sometimes flowing down, sometimes chaotic. I'm thinking about buying into the UAS if run logically with reference to this thread.

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    Well that one scrubber build that had the skimmer pump blowing water through a chamber with the screen flopping in it like a flag would be the closest to what you are getting at. Maybe something along those lines. I have been searching all over for the thread with that particular build in it. Anyone remember it?

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