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Ashland NFWCO
 Midwest Region
 MTAN Logo Dedicated To The Tribal Aquaculture Program Image of fish jumping.
      September 2004-Volume 49
 http://www.fws.gov/midwest/ashland/mtanhome.html **Coordinator:
          Frank G. Stone 
          (715-682-6185) Ext.
          202
          U.S. Fish and
          Wildlife Service
          Email: 
          [email protected]**
        
        **Edited
            By:
            Elizabeth W. Greiff 
            (715-349-2195) Ext. 141
            St. Croix Tribal Nat. Res. Depart.
            Email:**
                    **[email protected]**
 Topics
  Of Interest:  Keep a Lid on It!  Global Shelters by WeatherPort Lake 
    Aeration Diffusers and Aeration/Destratification Systems  Do 
    you need an outside covering over your  spawning area?  Do you long for 
    a portable covering for a workshop area?  Do you dream of a covering over your 
    outside broodstock ponds, fish distribution truck or pumping station?  The MTAN has worked under WeatherPort shelters 
    for several years and have found them to be very useful structures.  If 
    your fish culture operation would benefit from such an improvement, you may want 
    to consider these shelters for your aquaculture needs. Outdoor Fish Culture Sheltersby:
  WeatherPortEmail,  
  888-970-6411 or 800-569-1804 Outdoor Shelters by WeatherPort Global Shelters understands that 
    special situations exist where WeatherPORTs are needed. With decades of 
    experience our capabilities extend far beyond our standard line to provide a 
    custom structure designed and engineered for your specific applications.  Technical Specifications Doors:
    Standard options include single zip entries, double zip roll-up doors, solid 
    locking personnel doors (steel or fiberglass/aluminum), fabric or metal fold-up 
    doors, metal roll-up doors, equipment openings, vehicle doors, hangar doors, 
    double personnel doors, and sliding doors - all available to be included for 
    your project.
  Sealing/Insulation:Double layer liner-insulation systems rated from R-6 to R-30 depending on your 
    needs. These structures can be sealed completely for environmental control 
    purposes.
  Ventilation:
    Zip screened vents, roll-up screened side/strip vents, vertical drop/roll-up 
    curtains, electric fans, blowers, roof turbines, heating/air conditioning are 
    all available to meet your requirements.
  Lighting:
    Our non-block-out fabrics transmit approximately 40% of the natural light that 
    is diffused and is typically sufficient for most day time operations. We can 
    incorporate skylight fabric into the end panels or cover panels as well as 
    provide clear windows and any conventional lighting system that is available on 
    the market. Our screened vents also afford good light infiltration.
  Frame:
    Small Structures include a full-perimeter galvanized steel base, 
    pre-drilled for anchors, and an all slip-fit, self-aligning galvanized steel 
    framework - very strong, very durable. Interchangeable frame components. 
    Curved Arch units use 1 round structural steel, 17 ga. 
    Standard Soft Curve Gable units use 2 square tubular structural steel,15 ga. 
    Heavy Duty Soft Curve Gable units use 2 1/2 square tubular structural steel, 12 
    ga. No bolts or screws.
    Large Structures are fully engineered with modular, self-aligning, 
    trussed arch designs. Complete with galvanized or coated structural steel main 
    framework with aluminum fabric tracks - very efficient, very strong, very 
    durable. Interchangeable components. Versions for all snow and wind loads. See 
    Technical Specifications Tables for widths, module sizes and load ratings. 
    Custom sizes available. Fabric: 
  Several types of fabrics are available, all are UV resistant and meet various 
  fire codes. All fabric seams are heat or electronic welded. Fabric is attached 
  to frame via aluminum tracks and cable, cable or webbed ratchet tensioning 
  systems. Fabric options include: 18 oz. durable vinyl (PVC) coated polyester with a life span of 9-15 years.
    24 oz. long life structural vinyl coated/special treated fabrics typically used 
      for permanent installations: 12 to 20 year life span. Colors:White, Tan, Grey, Blue, Red, Yellow, Green, Translucent-Clear and other colors 
  available, including camouflage, olive drab, including light block-out. Accent 
  stripes or color combinations are also available.  Anchoring:
  Small Structures use a full-perimeter base that is pre-drilled and can be 
  staked to the earth or asphalt, or bolted to wood or concrete. The site 
  conditions, load requirements and your portability needs determine the anchoring 
  required.
  Large Structures- Every arch sets on a steel base pad which is predrilled 
  and can be staked to the earth or asphalt, or bolted to concrete. Usually 
  concrete footings or pad are not required. Warranty: Five year warranty on frames and vinyl fabric; three year warranty for vinyl 
  clear translucent and polyethylene fabric; longer pro-rata warranties on special 
  fabrics.  Installation: 
  All joints are self-aligning and convenient to assemble. All units include 
  complete instructions and free 800# support. Full turnkey installation also 
  available. Delivery:Usually 3 to 6 weeks depending upon stock supply and production schedules at 
  time of order.  Taxes/Permits/Fees: These structures are frequently used on a permanent basis; they are usually 
  classified as temporary structures and are not subject to property taxes, 
  however, local restrictions may apply. Commercial/Public uses may require 
  permits and wind/snow load data or fire certification.  Custom Design and Size: Aluminum or steel frame
    Arch spacing to meet your wind and snow 
      loads
    Truss or single arch
    Porticoes, partitions, vestibules, lean-tos, domes
    Variety of entry options
    Zippered entries (Single or double)
    Slam latch entries
    Panic hardware
    Glass, metal or wood
    Sliding glass doors Windows: Zip screened vents
    Sliding glass windows
    Aluminum or vinyl clad
    Jeep clear plastic Cover options: Black out vinyl
    Camouflage vinyl
    Arctic canvas or vinyl
    Insulation package  Lake 
  Aeration Diffusers and Aeration/Destratification Systems
  The following information was obtained from
  Aquatic Eco-Systems, 1767 Benbow Court, Apopka, FL 32703, 
  
  (407) 
  886-3939, 24 Hour Fax  (407) 886-6787, Email [email protected] The air diffusers used will determine the 
  overall efficiency of a lake aeration/ destratification system. The two most 
  common styles are the synergistic airlift assembly  and the 
  rubber membrane diffuser. Each was designed for different tasks. The synergistic 
  airlift assembly (SAM) is made to lift a large volume of bottom water, thus 
  removing stratification. The rubber membrane type (RM) was designed to aerate 
  wastewater. Synergistic Airlift DiffusersDestratification is the most economical form 
    of lake aeration. This is only accomplished by moving large volumes of water. 
    The synergistic airlift assemblies were developed through extensive underwater 
    flow testing to lift the maximum amount of water from above the diffuser to the 
    surface of the lake with a minimum amount of air (8,000 gpm/hp). This technique 
    requires a specific spacing of the individual diffuser fingers to provide 
    non-turbulent entrainment of the bottom water into the column of rising bubbles. 
    For that reason, each diffuser is optimized for a specific depth range. The smaller 
  ALA4 manifold is designed for 
  shallow lakes from 4 to 8 feet in depth. These shallow depths cause short 
  circuiting of the lifted water back to the diffuser, which limits their 
  effectiveness. Therefore, more diffuser manifolds per surface acre of water are 
  required than for a deeper lake of the same size. The ALA6 diffuser manifolds are best used in 
  water 8 to 40 feet deep. The deeper the water, however, the greater volume of 
  air that needs to be used by each diffuser. This is true for all diffusers. The 
  ALA8 diffuser manifold is typically used in water deeper than 30 feet.  The system is simple, safe and virtually maintenance-free. It is the most 
  effective lake aerator made! As little as 3/4 horsepower can be used to properly 
  aerate a eutrophic 10 acre lake! Rubber membrane diffusers are not designed to 
  lift water for destratification, so they are not recommended for lake aeration. 
  If used for lake aeration, many more of them must be used to achieve the same 
  result as a single synergistic airlift assembly. Synergistic Airlift DiffusersWhen the rubber membrane diffusers are used in 
  saltwater or wastewater, they may operate for a year or more in clean, soft 
  water without clogging. After that, remote cleaning can be accomplished by 
  doubling or tripling the amount of air delivered to a diffuser. This will blow 
  up the rubber, as in a balloon, dislodging the fouling matter. Wastewater 
  treatment plants are designed for this, but it may be impractical for lake 
  applications, where there is only one compressor.  Sometimes, rubber membrane diffusers will tear, greatly reducing their oxygen 
  transfer ability. If detected, retrieve the diffuser and replace the rubber 
  membrane. The ceramic diffusers used on SAMs should be inspected every three years. Clogging can be detected by recording the air pressure when new, 
  then annually checking the pressure to see if it has increased. Diffusers can be 
  cleaned by pouring muriatic acid into the airlines and turning on the 
  compressor. The original pressure will be quickly restored and the small amount 
  of acid will be diluted and have no effect on the lake. Technically Speaking ... When oxygen levels are low, you can 
    expect transfer performance of more than 10 pounds of dissolved oxygen per 
    horsepower! (Pumps, fountains and "air bubblers" are typically less than 2 
    pounds per horsepower.)
    Bubbles expand and spread out as they 
      rise. The column of water entrained within the bubbles from a synergistic 
      diffuser rises at about a foot per second, moving 2,000 gpm from the area 
      above the diffuser. (A drilled pipe diffuser with the same air volume would 
      move only about 200 gpm.)
    The surface boil  created by the 
      kinetic energy of the rising water  rises approximately two inches above the 
      surrounding water level. From there, the water rushes outward until its energy 
      has dissipated, sometimes traveling more than 100 feet, depending upon 
      temperature, surface tension and wind.
    The 
      lake surface tension is ruptured in the boil area. Supersaturated gases, 
      including carbon dioxide and hydrogen sulfide, escape from the bottom water 
      and oxygen is absorbed.
    There's no danger to swimmers, 
      boaters or aquatic life  even a marking buoy is unnecessary.
      Synergistic Airlift DiffusersAnd, 
      like hundreds of others, you'll enjoy watching the surface "spring" boils. 
      There is no electricity in the water.
    It's best to install the system prior 
      to stratification. If the volume of anaerobic bottom water is greater than 1/6 
      of the lake's total volume, contact AES for start-up instructions.
    Every lake is different. An AES 
      aeration specialist will be happy to assist with equipment selection and 
      system design. We'll need to know the lake's shape, size, depths, history, 
      bottom type, water source, flow, etc.  Related Links:
          Great LakesPond Aeration Systems,
  Great Lakes aeration/destratification system  How to Clean Sweetwater Diffusers The Sweetwater air diffusers, made of glass bonded silica, are virtually 
  indestructible and will give many years of service. The only maintenance normally required is periodic cleaning. The frequency of 
  cleaning will be determined by the mineral and organic content of the water in 
  which the air diffusers are used. In clean, cold, soft water, cleaning may only 
  be necessary every 2 or 3 years. In very hard water or water high in organics, 
  it could be necessary as often as every 2 months. Remove from service and blow out excess water. If fouled with  
    foreign material, scrape or hose off.
    Immerse completely in undiluted muriatic acid for a sufficient time to 
      dissolve the clogging material. If you have a 1/2" NPT white fitting on the 
      end of your diffuser, we recommend immersing the diffuser only, not the 
      fitting. This may take from one minute to eight hours in the most extreme 
      cases. Be very careful when using acid! Wear eye, face and hand protection and 
      have clean water available for rinsing and acid diluting in the case of an 
      acid splash or spill.
    After the clogging material has been dissolved, rinse thoroughly before 
      reuse.
    Discard the used acid by first reducing its strength to a neutral pH, by 
      diluting with at least ten times as much water as acid.  **Return
    to MTAN selection pageReturn to Ashland FRO home pageReturn to Region 3 U.S. Fish and Wildlife Service** Product and company
      names mentioned in this publication are for informational purposes only.
      It does not imply endorsement by the MTAN or the U.S. Government.
 Last updated: 
		  November 19, 2008
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