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Frequently Asked Questions
Q. What happens to water when it is aerated?
A. Aeration of water increases dissolved oxygen levels, removes gases or oxidizes impurities, such as iron and manganese. The water constituents that are commonly affected by aeration are:
Volatile organic chemicals, such as benzene, found in gasoline, or trichloroethylene, dichloroethylene, and perchloroethylene, examples of
solvents are used in dry-cleaning or industrial processes.
Hydrogen sulfide (rotten-egg odor)
Iron (will stain clothes and fixtures)
Manganese (black stains)
Various other chemicals causing taste and odor
Carbon dioxide is a common gas produced by animal respiration. Apart from being naturally present in the air, it is produced by the combustion of fossil fuels. It is used by plants in the photosynthesis process.
Surface waters have low carbon dioxide content, generally in the range of 0 to 2 mg/l. Water from a deep lake or reservoir can have high carbon dioxide content due to the respiration of microscopic animals and lack of abundant plant growth at the lake bottom.
Concentration of carbon dioxide varies widely in groundwater, but the levels are usually higher than in surface water. Water from a deep well normally contains less than 50 mg/l, but a shallow well can have a much higher level, up to 50 to 300 mg/l.
Excessive amounts of carbon dioxide above a range of 5 to 15 mg/l in raw water can cause three pond problems:
It increases the acidity of the water, making it corrosive. Carbon dioxide forms a weak acid, H2C03 (carbonic acid).
It tends to keep iron in solution, thus making iron removal more difficult.
It reacts with lime added to increase pH, causing an increase in the amount of lime needed to control pH.
Most aerators can remove carbon dioxide by the physical scrubbing or sweeping action caused by turbulence. At normal water temperatures, aeration can reduce the carbon dioxide content of the water to as little as 4.5 mg carbon dioxide per liter.
A poisonous gas, hydrogen sulfide can present dangerous problems in water treatment. Brief exposures--less than 30 minutes--to hydrogen sulfide can be fatal if the gas is breathed in concentrations as low as 0.03 percent by volume in the air. The Immediate Dangerous to Life and Health (IDLH) level for hydrogen sulfide is 300ppm.
Hydrogen sulfide occurs mainly in groundwater supplies. It may be caused by the action of iron or sulphur reducing bacteria in the well. The rotten-egg odor often noticed in well waters is caused by hydrogen sulfide. Hydrogen sulfide in a water supply will disagreeably alter the taste of coffee, tea, and ice. Hydrogen sulfide gas is corrosive to piping, tanks, water heaters, and copper alloys that it contacts. Occasional disinfection of the well can reduce the bacteria producing the hydrogen sulfide.
Serious operational problems occur when the water contains even small amounts of hydrogen sulfide:
Disinfection of the water can become less effective because of the chlorine demand exerted by the hydrogen sulfide.
There could be corrosion of the piping systems and the water tanks.
Aeration is the process of choice for the removal of hydrogen sulfide from the water. The turbulence from the aerator will easily displace the gas from the water. The designer of the system needs to consider how the gas is discharged from the aerator. If the gas accumulates directly above the water, the process will be slowed and corrosive conditions can be created.
Methane gas can be found in groundwater. It may be formed by the decomposition of organic matter. It can be found in water from aquifers that are near natural-gas deposits. Methane is a colorless gas that is highly flammable and explosive.
When mixed with water, methane will make the water taste like garlic. The gas is only slightly soluble in water and therefore is easily removed by the aeration of the water.
IRON AND MANGANESE
Iron and manganese minerals are commonly found in soil and rock. Iron and manganese compounds can dissolve into groundwater as it percolates through the soil and rock.
Iron in the ferrous form and manganese in the manganous form are objectionable for several reasons. Water containing more than 0.3 mg/l of iron will cause yellow to reddish-brown stains of plumbing fixtures or almost anything that it contacts. If the concentration exceeds 1 mg/l, the taste of the water will be metallic and the water may be turbid.
Manganese in water, even at levels as low as 0.1 mg/l, will cause blackish staining of fixtures and anything else it contacts. Manganese concentration levels that can cause problems are 0.1 mg/l and above.
If the water contains both iron and manganese, staining could vary from dark brown to black. Typical consumer complaints are that laundry is stained and that the water is red or dirty.
TASTE AND ODOR
Aeration is effective in removing only those tastes and odors that are caused by volatile materials, those that have a low boiling point and will vaporize very easily. Methane and hydrogen sulfide are examples of this type of material.
Many taste and odor problems in surface water could be caused by oils and by-products that algae produce. Since oils are much less volatile than gases, aeration is only partially effective in removing them.
Oxygen is injected into water through aeration. It enhances biological nutrient removal controlling algae growth while increasing water quality so it can support higher life forms like fish. The amount of oxygen that the water can hold is dependent on the temperature of the water. The colder the water, the more oxygen the water can hold.
Q. Do solar panels work in the rain or on cloudy days?
A. Yes, as anyone who has received a sunburn on an overcast day can tell you, much of the suns UV light still gets through tothe earth even if there are clouds in the sky. Its that same UV light that is mostly responsible for creating energy in solar panels. However when it really gets dark and rainy, while panels do still produce energy, they produce quite a bit less.
Here are some examples of potential panel efficiency changes:
Cloudy & raining 40% 90% drop in efficiency depending on how dark & heavy the rain & clouds are.
Heavy San Francisco fog 15%-20% drop in efficiency
Light San Francisco fog 8%-15% drop in efficiency
Age of the panels 0.5%-1% drop per year
dirty panels 1%-5% drop in efficiency
So even if you live in Seattle, or the frequently foggy San Francisco, you can still make use of the suns UV rays and go solar!
Q. I want to use my own solar panels/pumps and design/build my own experimental pond aeration system.
A. If you have line power available and you want the lowest capital equipment costs simply go with grid (plug-in) electrical power. Go to www.Grainger.com and search "ponds." Your grid power capital equipment cost from Grainger will be 50% less than any solar powered unit. However, there is a trade-off for power costs. Your power bills will increase by at least 30% (this means much larger pumps) for every diffuser and air hose you add via valved manifolds or your air flows will be reduced equally. For each valve you add you can count on doubling your maintenance efforts and cost as well. For most pond owners, a few hours each month of pump system maintenance effort sucks all the fun out of owning a pond.
Next, if you have no grid power closer that 100 feet or so, you may have to go solar or hybrid. If you are looking into windmill aerators remember they seldom work on lazy summer evenings when they are needed most. If you already have a windmill aerator, see our windsols hybrid units. Windsols patented units were built to take maximum advantage of published studies showing that aeration increases with natural wind and solar hybrids as high as 15000%.
Click here for links to instructions from the Canadian Environment on building your own solar powered aerator system using a diaphragm air pump mounted on a small trailer. Note: These home made 1.0 cfm solar aeration systems can vary from as low as $1,200 (with no battery storage) to $2,500 - $8,500 for 24-hour aeration..
Or click here for a USDA Inks Dam National Fish Hatchery design using a 35 watt diaphragm air pump, solar panel, and wood pallet to effectively aerate and mix a 1 acre fish pond in Texas for under $1500.00. This 1 cfm/acre diffused aerator design replaces a 1 HP diesel powered paddle wheel aerator with free solar power. A significant and cost effective design.
Both of the above designs work well in good weather and show good design costs under $1,500 for daylight only operation to +$8,500 for 24-hour aeration. Compare those costs to our PEC 1.0 cfm solar aerator costs here.
Please note: PEC only sells its distributed power systems and does not offer its aerator parts or services for designs by others. Our equipment will not work with your standard energy wasting, "old school," monolithic solar power designs. Our design requires two separate battery banks fed by two separate PV arrays using short 50-300 foot air hose lengths to supply air to dedicated diffuser(s) in the pond. We cost 60% less than monolithic designs because we use less than 60% of the power wasted by monolithic designs due to air control valves and long air lines. We use shorter hose lengths, shorter power transmission lines, and DO NOT use energy wasting air flow restriction valves to balance air flows to individual diffusers.
Q. Your competitiors say they are more expensive because they pump twice the air flow!
A. Not true! Our Eco-Aerators can be easily programmed by the user to pump twice the design air flow. Simply adjust the timers operating time to run both alternating air pumps at the same time using all the stored power in 20 hours or less!
Q. So, how do I get the right unit for my pond?
A. Start by assuming your clean water recreational pond is no worse than Reed Swamp. You need 1 cfm/acre of water for an average pond depth of 3-10 ft. Next, be assured that if you need more aeration than a swamp does, all our units can be upgraded by PEC with larger pumps using larger solar arrays and any supplemental aeration is better than no aeration at all.
The best method of aeration for recreational pond water quality improvement is to provide 1 cfm/acre 24 housrs each day. Although 5 cfm for 5 hours/day, may provide the same amount of total oxygen bubbled into the water it does not provide the same water treatment capability as constant aeration. Langston University Aquaculture programs demonstrate adequate oxygen and mixing with diffused aeration using 0.8 cfm for 1 surface acre of actively feeding fish ponds 3-10 ft deep. USDA Inks Dam National Fish Hatchery found that 1 cfm /acre using a single solar powered air pump and diffuser, in a 10 foot deep actively feeding fish pond, "found it mixes the entire pond and maintains high and constant oxygen levels." In comparison, studies on blast pumping large volumes of air into the pond for daylight only hours and then turning it off suspends solids and promotes development of a facultative bacteria, not an aerobic type of bacteria, that uses up the oxygen supply quickly when interrupted (they actually do this on purpose in sewage treatment plants to develop anoxic strains of facultative bacteria for denitrification) . Operating in an interrupt aeration mode can kill fish. Under aeration by start and stop aeration produces harmful algae strains, and promotes the growth of anaerobic deadly botulism bacteria dangerous to swimmers and ducks.
Think about it, do you think they actually turn off the aeration in the Chicago or San Diego Aquariums? Would you turn off the aeration in your home aquarium on purpose? Definitely not! Blast aeration is not equal to aerating for 24 hrs/day to improve water quality.
Q. Can you stop fish kills after they are already underway?
A. It is a myth to think you cannot stop fish kills after they are already underway! The only absolute truth about a fish kill underway is the dead fish will not only use up all the remaining oxygen in a pond, they will also stop the natural dissolution of any additional oxygen into the pond. No matter what the cause, your best response is aeration.
The quickest aeration response is our solar aerators. We can ship our largest units to reach you in 2-3 days. Place the solar arrays on flat dry ground facing a clear view of the southern sky. If you can open the boxes you can set them up and begin aeration in minutes.
Q. Where is the off switch?
A. The unit is designed to run 24/7, summer and winter. You never have to remove it from the water. The fish can't hold there breath any better than you can and become ill when oxygen levels get low. We do offer an automatic power down switch with our Hybrid Power Saver, pat. pending, for larger ponds to automatically reduce pump airflow when oxygen demand is reduced so we can increase stored solar power.
For smaller ponds, we do not recommend shutting off the aerator.
Q. What is your Hybrid Power Saver (pat. pending) and how does it work?
A. When it's windy, the natural oxygen diffusion in a pond typically does not need any additional supplemental aeration. We actually offer a Hybrid Aeration package sold separately that uses in-situ sunlight and wind velocity to vary aeration intensity creating large power reserves while maintaining adequate dissolved oxygen levels in a pond.
When you have enough wind to drive a windmill 24/7 you only need a tiny amount of that power to mix and destratify a typical 10 foot deep pond.
Both of our smallest EKBS-10 w/DT and EKBS-10A can easily do the mixing job at a much lower cost than a windmill.
Q. Can you help with monolithic intensive aquaculture designs based on using massive amounts of formerly cheap grid power and extremely high oxygen demand rates?
A. Maybe, but at PEC we focus on the "cloud aeration" approach using individual distributed power solar aerators. Our floating or fixed mount, self-contained, EKBS and G2V-STAR models are capable of supporting 0.1 to 10 cfm medium fine ceramic and ultrafine bubble (10-30 mm) membrane diffusers @ 1-15 foot water submergence or any water depth using our floating airlift draft tubes. The result is a distributed power sustainable aeration system with a low total cost of ownership, minimal annual maintenance, and the total elimination of mass system failures deadly to fish populations.
Q. Why do you build +25% power reserves into your standard G2V-STAR Solar Aerator units?
A. Your right, we could reduce the power reserves! However, we have learned from our 14 years of experience in manufacturing solar aerators for ponds that our units don't always get placed to take maximum advantage of the available sunlight. In fact, over 90% of our installations are in areas that only get direct sun from 10 am to 3 pm (mostly because we insist on this minimum solar requirement before the sale). Even when we do get placed in the most ideal sunlight conditions in New Mexico, were they get 30% more sunshine than our St. Louis solar designs, we end up with our solar arrays behind safety chain-link fence which reduces our actual power reserves.
Q. pH, CO2, Alkalinity, and Hardness?
A. Low dissolved oxygen (lack of aeration) is associated with all of the interactions of pH, CO2, Alkalinity, and Hardness in ponds. In extreme cases chemicals may be required in the short term, but aeration improves these interactions in the long term by adding oxygen and mixing while saving you money!
Q. Do higher water temperatures cause fish kills?
A. In the US, its not the temperatures that kill the fish! Fish thrive in water temperatures in excess of 100 F and Egyptian Tilapia reproduce well at water temperatures above 106 F. Its the lack of aeration (low dissolved oxygen levels) that kill fish. And even a tiny amount of aeration can save them!
Q. Solar vs. Grid Power?
A. Solar always wins because grid power gets interrupted and fish die in minutes without a (UPS) uninterruptible power supply.
Our G2V-STAR series solar aerators have a built-in power reserve capability of 30 days @ 4 hrs/day or 5 days @ 24hrs/day.
UPS for aquaculture, that works, is not really a choice. Our G2V-STAR series is the only low cost, SAFE, alternative.
Petro spills are a fish poison thats almost impossible to rectify and diesel/gasoline powered devices should not be used around any ponds.
Q. Is Grid Powered Aeration Cheaper?
A. Monolithic grid power aeration intensification designs are based on 30 year old technology that is based on cheap grid power. Distributed power design uses 10% of the air hose required by these typical monolithic designs. Because we need less air hose, we need less power to get the same amount of air into the water using exactly the same diffusers. And of course, with solar aeration, you don't get a power bill ever.
Q. Does your recommended airflow at 2 lpm (0.1 cfm) per 1/4 acre provide enough oxygen for my pond?
A. Due to the huge expenses involved in conducting full scale ASCE oxygen mass transfer testing on aeration equipment, only a handful of individuals have first hand knowledge of how vertical and horizontal flow developing aerations systems perform. PEC has conducted more than 200 such tests Internationally on ponds, lakes, lagoons, and tanks using splashers, fountains, bubbling diffusers, aspirators, propeller pumps, etc. We have always found, without exception, that all of these systems quickly establish a saturated oxygen "zone of influence" in the immediate area of the aeration device itself. We have also never found a mixing limited situation where any additional energy, beyond the aeration device itself, was needed for some oxygen dispersion throughout a contiguous body of water.
You will find from some aerator manufacturers, whose business is based on sewage treatment, tell you that you need lots of power and lots of high pressure compressed air to adequately aerate a body of water. Sewage water aeration designs are a massive overkill for recreational water treatment designs. Applying more than 1/2 horsepower of aeration per surface acre, 3-10 ft deep, will cause more damage than good to earthen basin recreational ponds. From a recreational and aquacultural design standpoint for pond aeration, USDA fish hatcheries and Canadian Environment studies show that using diffused air at 50 watts per acre foot is adequate for mixing and maintaining the higher oxygen levels needed for fish. As an example, a 190 lb. man needs 3-7 liters per minute of oxygen laden air to stay healthy, 190 lbs of fish need about the same. The manual pedal paddle wheel bicycle aerator, which has been supplying aeration for Asian Aquaculture for a more than a century. It typically provides less than 1 lpm of constant water/air contact(very similar to other grid or solar powered water circulators that develop high velocity laminar flows moving lots of oxygen bearing surface water with little or no turbulence so the layers of water slide like cards over each other with minimal oxygen transfer).
In comparison, PEC diffused air testing and other more in depth studies such as those conducted at a polluted stagnant Reed Swamp shows 30-250 mg/m2/hr per surface acre of oxygen demand. Oxygen demand is the amount of oxygen consumed and you need to apply several times that number to improve water quality. Wind driven normal wave action typically is limited to transferring less than 3 mg/m2/hr. Our EKBS-10 at 0.1 cfm (2 lpm) airflow can supply more than ten times that at 2500 mg/m2/hr of oxygen. Fewer than four EKBS-10 units per surface acre, thats one unit for each 1/4 acre of water, can easily meet this demand. Unless your pond is more polluted than Reed Swamp, an EKBS-10 provides plenty of oxygen for your small pond up to 1/4 acre, using our floating airlift aeration diffusers. If you actually have sewage flowing into your pond, the EPA recommends 0.5-1.0 cfm per thousand gallons of raw sewage. If you find that you have raw sewage flowing into your pond or need more air in the future, its as simple as adding another self-supporting PEC solar aerator. The additional power is still power bill free and unlike grid power, does not require expensive new power handling and distribution equipment.
Q. You offer both "bottom mounted diffusers" and "floating airlift aeration diffusers." Why?
A. Floating airlift aeration diffusers reduce the number of solar panels required and cut capital cost while only slightly reducing oxygen transfer. When using the free energy of the sun, your projected power costs are ZERO so the choice is really "cost of ownership." However, bottom mount diffusers are popular and asthetically pleasing. Here are a few specifics|:
1. Based on EPA studies, deeper placement of diffusers gives you higher oxygen transfer rates. You get a 1-2% increase in "clean water" oxygen transfer rates for every 1 ft. of diffuser submergence. Our airlift aerator has a diffuser at a submergence of 3 ft. If you take a diffuser and place it on the bottom of the pond (10 ft. vs. our floating diffuser at 3 ft), you will see an increase in oxygen transfer as high as 4% with a 400% increase in captial cost (more solar panels). Doesn't make much sense to operate deeper , driving up capital costs, when solar power is free!
2. When you put a diffuser on the bottom of the pond it will take more energy to get the same (or any) airflow. Therefore, you will need to increase the size of the solar array significantly.
3. A diffuser placed on the bottom of a pond will mix and destratify the thermal layers of a pond. The main drawback of bottom placement of diffusers is increased summer and decreased winter temperatures in bottom water stressing the fish and biota. More recent studies now focus on hypolimnetic aeration techniques supporting the use of floating air-lift aeration (draft tubes) as a management strategy to decrease the sediments oxygen demand while preserving thermal stratification zones and reducing stress on the fish and biota.
Q. Where do I place the floating or bottom mounted diffusers in my pond?
A. Placing a diffuser anywhere in the pond increases the oxygen and mixing everywhere in the pond by natural dispersion (higher oxygen around the diffuser and lower oxygen everywhere else). First, the main goal of diffuser placement is to locate it as far away from the overflow or discharge of the pond as possible. Second, place the diffuser(s) equidistant from each other and/or opposite shorelines closest to the inflow or influent water so the natural water currents can disperse oxygen throughout the pond. Last, attempting to add additional lengths of airline or place diffusers deeper than designed reduces aeration efficiency and/or eliminates airflow altogether.
Q. My problem is Algae. The pond used to be beautiful, What happened?
A. You have a build up of nutrients in the pond that needs more dissolved oxygen (aeration), period.
Eutrophication, a process whereby most older ponds and lakes develop excessive nutrients that stimulate excessive plant growth (algae and aquatic plants). Dissolved oxygen concentrations will severely decline when large amounts of algae (algal bloom) and aquatic plants begin to decompose. In turn, very low dissolved oxygen concentrations can cause fish kills.. Nutrients can come from many sources, such as fertilizers applied to agricultural fields, golf courses, suburban lawns, soil erosion, streambank erosion and sewage treatment plant discharges. The symptoms of eutrophication are:
Low Dissolved Oxygen Concentrations
Poor Water Clarity (Transparency)
Algal Blooms (Excessive Amounts of Algae)
Excessive Quantities of Aquatic Plants (Weeds)
High Dissolved Metal Concentrations (Iron & Manganese)
Stress to Fishery and Other Forms of Aquatic Life (Fish Kills)
High ammonia levels >5 mg/l, due to the Accumulation of Sediments
Nutrient Releases via Anoxic In-Lake Sediments
Buildup and Release of Noxious Odors & Toxins
Botulinum toxin (Avian Botulism)is a protein and neurotoxin produced by stagnant anoxic water borne anaerobic bacterium, Clostridium botulinum. It is the most acutely toxic substance known on earth. Sporulation needed to produce the neurotoxin is easily preventable with simple water aeration methods.
Harvesting algae as bio-fuel or fertilizer controls algae. Aeration at any level will also improve the water quality, reduce ammonia levels and decrease the frequency of algae blooms. Most chemical treatments only delay the need for aeration by chemically storing the nutrients as dead algae on the bottom of the pond. A few chemical treatments like www.ALGAEOUT.com work with solar aerators to remove the nutrient levels in the water so nothing is left over for the algae to thrive on. Ammonia levels are easily detectable with aquarium test kits from any fish store. The lowest cost method for removing ammonia is also solar aeration (air stripping). If ammonia levels spike they can be quickly lowered by broadcasting Zeocarbon by hand. Simply apply 10 lbs/acre (10 lb of Zeocarbon at standard temperature and pressure can absorb 2 lbs or >1 mg/l per acre ft. of ammonia) and re-test ammonia levels. Add more Zeocarbon as needed.
Q Our state agency does not encourage use of grid powered aeration or chemical additives and says to stop feeding my fish to prevent kills.
A We agree, somewhat! You need to aerate the pond and stay off the grid while doing it. It is Environmentally undesireable to aerate using power from unsustainable fossil fuel grid powered systems. However, not only is it desireable to use sustainable solar powered aerators to improve water quality, remove nutrients/pollutants, control algae, enhance fish production, and control insect breeding, it is putting Reconciliation Ecology into actual practice.
Q. How much mixing do I need?
A. Published studies demonstrate less than 0.15 cfm of diffused air per surface acre is needed to maintain oxic sediment in a 1 acre pond, 10 feet deep. Ponds are almost never mixing energy limited when you are adding aeration to improve dissolved oxygen levels. Maintain mixing energy under 750 watts/acre and airflow levels under 1 cfm/acre will allow solids to settle and prevent turbid or cloudy water conditions that could block out the sun, stop natural biological processes and destroy the ponds highlife.
Q. How much dissolved oxygen do I need for fish and algae control?
A. You need to maintain the dissolved oxygen in a "fish safe zone" from 3-5 ppm at all times, night and day, to prevent fish kills. In a typical fresh water pond that typically means less than 1 cfm per surface acre for most game fishing ( +6 cfm for trout).
Biologists at Inks Dam Natioanl Fish Hatchery have completed their pilot study and know the optimum size and power requirements for aerating one-acre game fish ponds using solar power. Aeration helps prevent fish kills during the hot Texas summers when dissolved oxygen levels can plummet in ponds. Combining a centered 120-watt photovoltaic panel with a 1/8 horsepower pump and bottom mounted 9-inch disc air diffuser mixes the entire pond and maintains high and constant oxygen levels all summer in Texas.
PEC recommends a minimum of 60 watts per surface acre (2 of our EKBS-15 units) when fish are not being actively fed.
Q. I still want a fountain or a splasher to look at?
A. Both Splashers & Fountains are pretty to look at, but you would have to surround your pond with solar panels to make them work at all. Then you would have to pull weeds off the pumps, filters, and props everyday. Every boater knows you spend an hour cleaning the weeds off the prop on every outing. The maintenance on mechanical splasher/fountain aeration is DAILY. Other than sinking a well and using high pressure well pumps the only no maintenance or "low" maintenance aeration method is diffused aeration (bubblers).
For more information or questions about our products & services, please contact us at the following address.