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Thread: Dual Screen Horizontal Scrubber

  1. #1

    Dual Screen Horizontal Scrubber

    Due to popular demand I have taken some pics and built my scrubber in Sketch Up to share my experiences.

    Due to current set up and space constraints I decided to go down the horizontal route for my scrubber.

    One thing I wanted to avoid was a poor performing scrubber so I opted for a design which had two scrubbers with one effectively running on to the other.



    This picture shows the inlet and the layout of the two screens and the lights. The lights are placed on a glass sheet which is about 2-4", allowing for the incline, above the screen.



    Here is a different angle shot.



    And this image shows the waterline. The second screen sits just below the water level which means the scrubbers is silent.

    Its hard to take actual photos due to the covering on the tank but I have taken a cople of shots of the screen:





    The large scrubber was cleaned on sunday and the small on yesterday.

    You cant really see from the photo but the small screen which has reduced water flow over some of its surface is producing tough green algae and the larger one is producing the same and a darker algae.

    I originally intended changing the second screen to ensure the flow was consistent across its surface but the different algae got my attention.

    On saturday whrn I clean the larger screen I will get some shots for you all and I would welcome any comments you may have.

    Keith

    ps apologies for the links but the img command didnt work with picassa, anyone with suggestions to fix this will be welcomed!
    sorted!

  2. #2

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    Re: Dual Screen Horizontal Scrubber

    Hi, have been looking into making a horizontal scrubber as I think it's easier to light and less splashing.

    Are you still using two sheets of plastic canvas sandwiched together?

    I have a sheet of opaque acrylic about an 1/8th inch thick which I may use as the base for the screens to lay on, it will also at as a reflector to some degree.

    I have a DSB with some macros growing in it, so the acrylic sheet will block most of the light to the DSB and macros and it will slowly die off I assume? But as the ATS will eventually out compete the macros I guess they would die off anyway due to lack of nutrients?

    My only concern is would there be a detrimental effect on the DSB and the various bugs and critters that live in it, due to the reduction of light? Just wondered if you might know or anyone else that reads this reply?

    Cheers, John

  3. #3

    Re: Dual Screen Horizontal Scrubber

    I am using a very rough gouged and generally abused sheet of acrylic with a single layer of mesh.

    I was using the acrylic alone with good results and added the mesh recently and it exploded with growth! I tried two sheets but I didn't like what it did to water flow as the top layer was out of the water.

    With regards to the DSB I don't think the critters will be affected too muc as the DSB doesn't IMO need light as it will not penetrate that far in.

    I too have a DSB below my screens and it has only had a positive effect on critter populatio, check out my thread on bio diversity.

    Hope this helps!

  4. #4

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    Re: Dual Screen Horizontal Scrubber

    Hi, great thanks for that bit of info. I meant to ask if you had a DSB but you answered it for me. I see what you mean about two screens and the upper one being lifted clear of the flow, good point. I read the bit on Bio-diversity, seems nothing but positive results from these algae scrubber contraptions!

    My system is about 120 uk gallons including the sump which is 36x15x18 inches I will only be able to use the central area to install my scrubber.The screens I have are 13.5 x10.5 inches ( from Hobbycraft ) which give me approx 142 sq inches per side. I think will have to make the secondary screen smaller like yours to be able to fit it all in and get light to it, so it should be more than enough surface area?

    I have a NuJet 1700 which give 1700l per hour 374 gallons per hour, if thats not enough then the Ocean Runner 2500 thats currently running the skimmer will come into play.

    Many thanks for the info

    John

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    Re: Dual Screen Horizontal Scrubber

    Are there actually pictures? Wonder why I can't see them..

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    Re: Dual Screen Horizontal Scrubber

    Congrats on getting your scrubber up and running.

    Due to current set up and space constraints I decided to go down the horizontal route for my scrubber.
    A horizontal takes up more room, not less, for the same processing.

    One thing I wanted to avoid was a poor performing scrubber so I opted for a design which had two scrubbers with one effectively running on to the other.
    You actually described how to make a less-performing design, not a more-performing one. A more-performing design has high flow, near lights, and a wide but short screen (the opposite of what you have). Also, having one screen dump to the next is just providing already-filtered water to the next one. A two-sided vertical screen would provide the same filtering in 1/5 the space that you have here, and with 1/3 the wattage.

    Your lights need to come down, to within 4" of the screen. A single bulb at this distance would provide the same filtering as the 6 bulbs you have now.

    You cant really see from the photo but the small screen which has reduced water flow over some of its surface is producing tough green algae and the larger one is producing the same and a darker algae.
    This is because you have variable light, and variable flow, across the screen. In other words, much of your scrubber is doing nothing at all... just taking up space... which is the opposite of what you were trying to do (save space).

    Hi, have been looking into making a horizontal scrubber as I think it's easier to light and less splashing.
    No, it's not easier to light PROPERLY. It's actually difficult to get the bulbs to within 4" of the screen, all the way across, on a horizontal design. Also, if horizontal, you'll need TWICE the size since it's just one-sided. Lastly, flow is very difficult to get even and rapid. Slow, variable flow will actually cause problems, since the water will divert easily, and allow sections of new growth to die-off.

    But as the ATS will eventually out compete the macros I guess they would die off anyway due to lack of nutrients?
    If you do a horizontal with weak lighting, it will not out-complete. It will not be strong enough.

    I was using the acrylic alone with good results and added the mesh recently and it exploded with growth!
    Yes, because the algae does not let go as easy. Two layers is even better. Roughed up like a cactus is best.

    I tried two sheets but I didn't like what it did to water flow as the top layer was out of the water.
    Because you have low flow, which is the norm for a horizontal design. That is another reason why they need to be much larger that vertical designs... because they are weaker.

    My system is about 120 uk gallons including the sump which is 36x15x18 inches I will only be able to use the central area to install my scrubber.The screens I have are 13.5 x10.5 inches
    You only need one of those screens, vertically, to do the filtering. If horizontal, you'd need at least two, preferably three.

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    Re: Dual Screen Horizontal Scrubber

    If a pump is pushing out 'X' amount of water it does not matter if the outlet is verticle or horizontal...gravity is not going to pull more water through the pump wether horizontal or verticle...is it? The emitted water, once it is going over the screen may fall quicker in a verticle ATS but in a horiontal design the water physically cannot escape as quickly so surely the water build up is more turbulent once algae has grown? What has a rougher flow of water, a waterfall or rapids? The verticle design is having to split the pumps output over two sides, not one, so is it not logical that each side on a verticle design is getting half the flow that any given pump produces per side? Surely a horizontal design is getting the pumps full flow rate over one side? Am I missing something here? I can see that a verticle design takes up less space....other than you have to find space for lights on both sides of the screen that are going to be at a maximum 8 inches apart and there's going to be more splashing and noise, dependant I admit, upon actual design. A horizontal design has all the lights on one side so you are getting the same intensity of lighting but it's all on one side..more light equals more growth? On a verticle design each side is getting just half the light per side of a horizontal ATS. Maybe my maths needs a bit of a scrub up...no pun intended :lol: If it's turbulance that makes the algae grow then just add a few obsticles to hinder the flow of water, ie plastic pegs, square, round ,triangular, just like boulders in a river = White Water.

    All commercial scrubbers I have seen, sewage, swimming pools etc are of a horizontal design allowing maximum contact time between the contaminated water and the algae. As with protein skimmers the contact time between the micro bubbles and the contaminated water is what gets the resultant foam. Also with UV sterilizers, exposure time of the water to the UV light is what makes it work, too fast a flow and it will not be efficient and you will be wasting your electricity!

    Just a little food for thought, check this commercial ATS site out...all horizontal http://www.algalturfscrubber.com/point.htm An interesting read about Global warming too.

    At the end of the day I guess the proof of the pudding is in the tasting? If it works don't fix it :!:

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    Re: Dual Screen Horizontal Scrubber

    If a pump is pushing out 'X' amount of water it does not matter if the outlet is verticle or horizontal...gravity is not going to pull more water through the pump wether horizontal or verticle...is it?
    It's now how much water comes out of the pipe; it's how thin and rapid it is. Vertical is much thinner and more rapid.

    What has a rougher flow of water, a waterfall or rapids?
    Waterfall. You will not get "rapids" in a horizontal. And it's not how rough it is on the surface; it's how rough it is at the screen.

    The verticle design is having to split the pumps output over two sides, not one, so is it not logical that each side on a verticle design is getting half the flow that any given pump produces per side?
    How much water has nothing to do with how rapid it is. Vertical keeps it thin and rapid. Horizontal keeps it in a puddle.

    Surely a horizontal design is getting the pumps full flow rate over one side?
    Yes but's it's usually a puddle, unless you tilt it up 45 degrees or more.

    there's going to be more splashing and noise,
    There is no noise if done properly. And a horizontal will probably splash more.

    A horizontal design has all the lights on one side so you are getting the same intensity of lighting but it's all on one side..more light equals more growth?
    Provided you have the flow. And provided the light NEAR the screen. It's just now being understood how important flow and a rough screen are.

    If it's turbulance that makes the algae grow then just add a few obsticles to hinder the flow of water,
    This would stop the scrubber altogether.

    All commercial scrubbers I have seen, sewage, swimming pools etc are of a horizontal design allowing maximum contact time between the contaminated water and the algae.
    They have endless sunlight, and real estate, to make up for weak filtering.

    All commercial scrubbers I have seen, sewage, swimming pools etc are of a horizontal design allowing maximum contact time between the contaminated water and the algae.
    With scrubbers, it laminar flow.

    Also with UV sterilizers, exposure time of the water to the UV light is what makes it work, too fast a flow and it will not be efficient and you will be wasting your electricity!
    See here: viewtopic.php?f=9&t=286

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    Re: Dual Screen Horizontal Scrubber

    ThePisces; Don't be deswaded. I commend your efforts and hope you proceed. Only thru different topologies will we arrive at various effective choices for TS. One type will never be the 'for all systems' solution.

    I think that if you have little vertical space available then it matters not that vertical scrubber is more surface efficient. It may still be a non-starter.

    I also think that the jury is still out on horizontal scrubbers. Nixing them outright because vertical plastic screens work well is not conducive to improving the subject of turf scrubbers or making available horizontal ones useful in some physical locations.

    Flowing one screen onto another is not going to be detectably less efficient. The amount of nutrient take up is only a VERY tiny amount of nutrients on any particular pass across the screen. You could not measure the difference in the prescreen verse post screen concentrations. It is the fact that there are endless passes that provides for the continuous reduction in nutrient levels.

    Turbulent pulsed flow is going to exchange more boundary layer water than fast laminar flow. This is why Adey went that way.

    Single sided screens are no less efficient than two sided screens. They have the same surface area. They need the same light intensity. You need two times the water. I'm not even convinced they are more space efficient. Having light fixtures on both sides make two sided verticals bulky.

    Keep us posted ThePisces!

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    Re: Dual Screen Horizontal Scrubber

    Thank you Kcress for your 'Positive' comments in which you have not dismissed what industry and other scrubbers have found in using the horizontal design. If verticle was greatly more efficient then why has industry with all the space and goverment funding they have, not gone down that route?

    Verticle scrubbers are as you rightly say 'Bulky' due to lights on both sides. The fact remains that horizontal scrubbers have all the flow on one side and not divided over two sides and all the lighting is on one side.To light a verticle screen to the same intensity as a horizontal screen you would need twice the number of bulbs or higher wattage bulbs ($$$) With a slight incline as in Worley's a 30 degree design ( closer to horizontal than verticle) seems to work fine as do others (Routestomarket) who adopt the horizontal version. A horizontal screen angled across a sump is going to have the same if not greater surface area compared to a double sided verticle screen in the same sized sump if height is restricted which it usually is, because you have a whopping great aquarium above it!

    How do you measure the size of a television screen? Across the horizontal, top corner to bottom corner, not verticle. That gives you more than double the verticle height. My 4 x 2 x 2 ft aquarium has a horizontal (top corner to bottom corner) measurement of approximatley 52 inches. The verticle is 24 inches. So surface area is greater in a horizontal design even if you double the verticle.

    The area my sump allows for a horizontal screen is 22in x 12 in. That gives me a surface area (one side only) of 264 sq inches. Which in my case ( allowing 1sq inch per gallon) gives me an excess of 144 sq inches of screen, or 2.2 sq inches of screen processing per gallon!

    Far from being put off from the horizontal design I will continue with an 'Open' approach to design and appreciate any constructive comments like yours on both verticle and horizontal designs. At the end of the day I doubt very much that there is any significant performance difference between the two options. If the nutrient levels are not detectable or very minimal you have achieved what you set out to do....Scrub!

    Kind regards,
    The Pisces

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