Below is general information about our SolarBee solar-powered and GridBee electric circulators for lakes and raw water reservoirs. In the left menu are links to more information on our two main lake applications, epilimnetic and hypolimnetic circulation. Also, the "Compare Flows" link graphically shows the differences between the two applications, and compares SolarBee circulators to other products available.

SolarBee SB Mixers
SolarBee SB Series
Solar Circulators
GridBee GF/AP Mixers
GridBee GF and AP Series
Electric Circulators

Medora Corporation's circulation technology has evolved to become the world's most proven self-sustaining technology for controlling harmful blue-green algae blooms, with a 90-95% success rate. Controlling these blooms has reduced taste and odor problems in drinking water, improved dissolved oxygen levels, helped prevent fish kills and improved overall water quality and aesthetics worldwide. The map shown above represents more than 1,200 SolarBee high-flow, long-distance circulators installed successfully in hundreds of lakes and raw water reservoirs. Each site has anywhere from one to twenty circulators installed, depending on the customer's objectives, surface area, nutrient levels, and other factors.


GridBee AP Air-Powered Mixer Video

Videos - GridBee AP
Air-Powered Mixers


U.S. Lake Locations Overview

U.S. Lake Locations Overview

Epilimnetic Circulation

Epilimnetic Circulation

Hypolimnetic Circulation

Hypolimnetic Circulation

Quiet Lake

Benefits: Long-distance circulation (LDC) equipment can be deployed to treat the epilimnion (above the thermocline), to prevent and control harmful blue-green algae (cyanobacteria) blooms and invasive macrophytes (weeds). LDC can also reduce taste and odor problems in drinking water, improve dissolved oxygen levels and pH levels, prevent fish kills, and generally improve water quality and aesthetics.

LDC can also be deployed to treat the hypolimnion (below the thermocline), to solve problems of iron, manganese, sulfide odors, arsenic, methylated mercury, and internal loading of phosphorus and nitrogen.

"Either / Or": Our circulators can be deployed in lakes to solve either epilimnetic problems or hypolimnetic problems. This "one or the other" characteristic is similar to a common hammer used by a carpenter; a hammer can be used to either pound in a nail or else pull a nail, but it can only be used for one purpose at any given time, not both at the same time.

Which path is your lake on?   Once a lake starts developing water quality problems, the problems usually get worse each year in both severity and duration. Here are possible courses of action:

Recreational Lake Installation

  • Doing nothing:  Sometimes this is the only approach possible, due to a lack of funding to restore the lake.  If this approach is taken, care should be taken to monitor the lake and post no-contact warnings when blue-green algae blooms are present.
  • Improved watershed management: Aimed at stopping phosphorus and nitrogen input to the lake, watershed management is a step in the right direction, and can sometimes slow down the rate of deterioration. But it virtually never reverses the trend or restores the lake to acceptable water quality. 
  • Chemical application: Constant application of chemicals to the lake is another path available.  This can appear to be a quick and simple solution at first glance, but is very expensive and not very effective. Herbicides generally devastate the lake ecology by killing everything, even the "good" bacteria and other organisms. Then a flood of nutrients is released from dead organic material which causes a worse problem several weeks later, leading to more herbicide being needed. Also, algae and plants build resistance to herbicides so that over time, even more herbicide is needed. Another proposed solution may be sequestration agents, such as alum, used to try to stop "internal loading" or re-cycling of phosphorus or nitrogen from the sediment. Despite various claims of the industry and its advocates, generally this approach confers no measurable benefit to the lake beyond the same year as the application, and there are very few lakes worldwide, most likely less than 10, where any longer term benefits were obtained from this approach in the last 50 years.
  • Long-distance circulation: There is one in-lake solution that is sustainable, affordable, and provides immediate and constant progress in restoring a lake to good water quality. That approach is long-distance circulation by SolarBee, now in use in over 350 lakes in the US, many of them for 5-10 years. Many customers tell us in the first year that their lake looks better than it has in  decades, and the lake continues to get even better every year after that.

SolarBee Lake Rainbow

What's the payback?  Of the approximately 350 lakes SolarBees have restored in the US, about 50% of them are source water for municipal drinking water plants. In many of these projects the SolarBees paid for themselves in the first year by carbon savings in the drinking water treatment plant and/or chemical savings in the lake.

Several customers with partial-lake treatment (directly in front of the plant) of very large lakes, with plant capacities ranging from 40-70 MGD (million gallons per day) are saving over $500,000 per year in plant operating costs compared to before they installed SolarBees.

The other 50% of SolarBee lakes are recreational lakes, where the homeowers are enjoying better swimming, fishing, and boating, and higher re-sale property values since installing SolarBees.

Equipment Features:

  • A scalable solution with applications in virtually every lake; SolarBees are restoring lakes from one acre to 10,000 acres with depths from two feet to over 100 feet. Sometime the whole lake is treated and other times, in a partial-lake application, just the high-value portion of the lake is being restored.
  • No infrastructure requirements. SolarBee systems can usually be designed in one week, and delivered and installed in 4-8 weeks.
  • Factory delivery and installation; annual service plans are also available.
  • Available on a "try-before-you-buy" pilot or rental basis, 95% of pilots convert to a purchase.
  • Long parts and labor warranty, from two years to 25 years depending on the machine model and component. All equipment has a 25 year design life.
  • Standard and optional equipment includes high-wave kits, Coast Guard approved beacons, on-shore SCADA monitoring, anti-jam and self-cleaning capability, data logging, programmable seasonal run times, algorithms for various latitude, and many other unique and necessary features.
  • For private companies purchasing solar powered mixers, there are extensive tax credits that greatly reduce the cost of the equipment.

SolarBee SB Series solar circulators: SB Series mixers are designed to operate 24 hours per day on solar power, utilizing digital logic for power management, auto-reverse and anti-jam features. These mixers are most typically used where power is not available or when the ponds are large in size.

GridBee GF Series electric circulators: GF Series mixers are the same machines as the SB mixers without the solar equipment; they are designed to operate 24 hours per day on 120v electric power. These mixers cost less and are typically used where power is readily available or when the ponds are smaller in size.

GridBee AP Series air-powered circulators:  AP Series mixers combine patented high-flow Long-Distance Circulation technology with a clog-free air-powered pump. They have no moving parts in the water and no electricity in the water.  Learn more

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