Further Pond UV Sterilizer/Clarifier Suggestions;
For Small Ponds, self contained Internal UV Sterilizers are growing in popularity, however I would caution prospective buyers that the first generation models have problems with electrical failure and are not efficient.
The newer 3rd generation Internal UV Filter/Pumps (such as the SunSun 13 Watt; picture to the left) are much improved, however even these are only best for ponds up to 1500 gallons (and this is assuming other filtration). In most real world ponds I would not use this past a 700 gallon pond and again this is assuming other filtration (although multiple units can be used together for larger ponds).
This said, for those desiring UV Clarification but not desiring to bother with plumbing, these Submersible UV Pumps are hard to beat.
These can also be used for larger ponds by strategically placing 2 or more of these UVs in as far apart from each other as possible.
I would also point out that while these UV/Filters do provide some filtration, this is intended primarily for pre-filtration prior to water entering the UV-C chamber.
The use of Volcanic Rock around your Internal UV filter is strongly suggested to prevent clogging by acting as a pre-filter. This will yield better results with your UV Clarification and add to your pond filtration.
Do not believe web sites or other dealers stating this is an all in one filter UV.
What the best of these is (such as the SunSun CUP-613 UV Filter); is a simple to use economical UV Sterilizer with filtration by itself maybe for a light bio load 100-200 gallon pond and otherwise additional filtration must be used (even a Hydro Pond Sponge Filter has vastly more bio capacity and would make an excellent inexpensive compliment to this UV Sterilizer.
For larger ponds (over 2000 gallons) often placing two UV Sterilizers such as two Terminator 36 Watt UV will be more economical than one larger UV Sterilizer as when used with separate pumps, the flow pattern is often better, therefore the pond "turnover rate" (how often the entire pond water passes through the UV Clarifier) is generally slightly higher than one unit of say 75 watts that often costs more than double the price as well.
The use of one pump with two UV Sterilizers (or more) can also work well, provided the returns are in different locations of the pond for optimum circulation and water turnover in the UV Sterilizer, however I have still achieved the best results when two or more UVs are employed by using separate pumps with intakes and returns in separate locations of the pond to optimize water flow patterns through the UV Clarifier.
For very high volume pumps or extra large ponds units such as the TMC Professional 110 Watt UV Sterilizer would be an excellent choice. This is probably one of the best UV Sterilizers in its class, with high water exposure time even at high flow rates, without paying for often useless gimmicks. Although the advertised flow rate maximum is 9600 gph, I personally only recommend half this (about 4800 gph), however this still allows for the largest of water pumps (especially once one considers loss of gph when head pressure is applied by lifting through water features and the UV itself). As well this would allow this UV Clarifier to work via turnover of pond once every 2-3 hours of a pond up to 12,000 + gallons.
I should also note that spending more money for a pond UV Clarifier with wipers or HO UV-C bulbs is often not money well spent, as the wipers are often gimmicks that easily break and do little even when functional. As well HO (high output) UVC lights often are very short and even with this higher output, these are often still not enough for the water flow that is usually applied to these UVs. For example, although a 50 Watt HO bulb of 18 inches will handle a higher water flow of a 25 watt UVC bulb of 18 inches, the flow rate is not doubled.
Better is a unit with long exposure such as the TMC Professional 110 Watt UV Clarifier as compared a Smart HO Two-Lamp 100 Watt UV Sterilizer or two TMC Pond Advantage Premium 25 Watt UV Sterilizer as compared to one Emperor 50 Watt UV.
The TMC Pro 110 Watt is not only vastly less expensive, it is a superior UV Sterilizer in terms of UVC exposure and performance, as well the TMC Professional 25 watt and more efficient yet TMC Pro Clear UV30 are recognized by many pond keepers in Europe (where these are the #1 premium UV Sterilizer) as one of the best UVs for their ponds and two of these Sterilizers often cost less than many gimmicky 50 watt UVs!.
For an article that deals with the question of pond filter placement in relation to a UV Sterilizer (as well as many other aspects of UV Sterilizer use), please follow this link:
Is the UV best placed after or before a filter in a pond
Another important consideration with the use of ANY UV Sterilizer for outdoor pond use is protection from direct weather exposure.
Despite some less than honest manufacturer claims, I have found that even UVs specifically designed for outdoor use succumb to the weather, often with damage to the ballast resulting in a UV Bulb failing to properly fire, especially a new premium hot cathode/low pressure bulb (these are much more efficient, but also require a higher voltage surge to fire).
My suggestion is to cover the UV Sterilizer with flat rock (such as pictured) or suspend the UV in a structure that protects the UV from direct weather.
Make sure to change your UV Bulb/Lamp once per season or twice per year in warm climates such as So. California or Florida.
If you have problems with a new UV Bulb firing, please see this video and or read this article:
UV Bulb Trouble Shooting Video
UV Troubleshooting Article
Finally, while I recommend a UV Sterilizer/Clarifier for most ponds, I find that many pond keepers are too dependent upon this device where as if the UV ceases to function the pond immediately turns pea soup green. In my experience this indicates a pond that also is in need of better filtration, as the UV Clarifier should be a compliment to good filtration, not make up for poor filtration. The Veggie Filter I suggested earlier is a good idea, or simply adding more filters if your pond has some filtration, but your current filtration is not adequate.
 POND ALGAE (Green Water and Blanket weed)
For MUCH more about the control, prevention and treatment of pond algae, please read this NEW article: Pond Algae; Green water and blanket weed
Also see this article for information specific to Cyanobacteria:
Cyanobacteria in Ponds
In a healthy pond, with a properly functioning nitrogen cycle, water changes can be minimal. I still recommend a water change of 10-20% per month on a healthy, fully functional pond. In a newer pond larger and more frequent changes may be necessary.
If your pond has a KH below 80 ppm and a pH below 7.0, I would first look to possible causes. One common one is the buildup of organic mulm on the bottom of the pond. The decomposition of this will produce nitric acids which will affect the pH and KH. Since most pond keeper have koi or goldfish, this is important to note, as both these fish do much better at a pH above 7.2 and need the calcium provided by the KH for proper osmotic function. See “Proper Calcium, Magnesium and KH in Aquariums” for more information about Calcium KH, and GH.
Here are a few determining factors for water changes in a pond:
*Nitrates- If they climb above 50 ppm
*Phosphates- If they climb above 1.0 ppm
*KH- If it falls below 80 ppm (assuming your tap/well water is higher)
*GH- If it falls below 150 ppm (assuming your tap/well water is higher)
If a lot of leaves fall to the bottom of the pond vacuuming them or raking them out is important to prevent organic buildup.
Water changes also will help with pH and KH if your tap or well water is slightly alkaline and has a KH above 80 ppm.
Your pond filter should also be part of your pond cleaning schedule. With a pressurized filter such as the Clear Stream Pond Filter I recommend cleaning and rinsing once per month during pond season or more often if the flow rate slows down.
Veggie Filters should cleaned and trimmed at least once per season.
 POND CYCLING:
Generally speaking this process is about 99% the same as aquarium cycling, so I would strongly recommend reading this excellent article:
The Aquarium and Pond Nitrogen Cycle, cycling
I would add in addition to this article that the process of cycling in a pond takes 6-8 weeks in warm months, but cooler temperatures such as a pond under 60 F can delay this process. The amount of bio media such as Volcanic Rock or Pond Matrix available can also affect this “break in” time. As noted above, the addition to a Veggie Filter can not only increase filtration capacity, but also improve your ponds cycling process.
Products such as Pond Stability can also aid in "kick starting" your pond, as well this product in particular with its synergistic blend of aerobic (including encapsulated oxygen), anaerobic, and facultative bacteria will also prevent and reduce pond sludge build up.
If your pond has been left with water, but no filtration or if you are moving a pre-fabricated pond from one location to another, do not assume that the essential aerobic bacterial that process nitrogenous waste (keeping extremely toxic ammonia levels low or 0) will immediately "bounce back". Adding aged filter media (as with aquariums) and/or NOT cleaning filters that are transferred other than a quick rinse with pond water or de-chlorinated tap water is essential to keeping a new or a re-set-up pond from having a deadly spike in ammonia.
 POND CARE BIOLOGICAL PRODUCTS
For sludge build up products such as SeaChem Pond Stability, Natural Environmental Beneficial Bacteria, Microbe-lift or PondCare Barley Clear are useful for aiding in the breakdown of sludge and other organic mulm through the action of bacteria and enzymes.
I have used and sold these products in my Aquarium and pond Maintenance business with fair results. They are good at aiding in the breakdown of sludge and improving filter efficiency, however it is not a cure all for poor filtration and pond maintenance and some claims in my opinion are somewhat over blown.
Of these products, the newest and most effective is SeaChem Pond Stability followed by Natural Environmental Beneficial Bacteria Blocks are easy to use and when used properly can be a compliment to other good pond maintenance procedures.
The reason I now recommend Pond Stability over the other similar products is its blend of synergistic blend of aerobic (including encapsulated oxygen) and facultative bacteria. The Facultative bacteria contained there in can adapt to both sludge removal and aiding in the very important nitrogen cycle of your pond (conversion of ammonia & nitrites to less toxic nitrates and eventually total removal).
It is important to note that many of these products are primarily Heterotrophic Bacteria and other enzymes, NOT the nitrifying Autotrophic bacteria necessary for a healthy nitrogen cycle (although Stability has facultative bacteria too & is more helpful to pond cycling).
Please see this article for very in depth information about the aquatic Nitrogen Cycle: “The Aquarium and Pond Nitrogen Cycle” (the article is officially titled “aquarium nitrogen cycle, however the information contained there in applies equally to ponds).
This is not to say these products are not useful as noted in the preceding paragraph, just not for seeding a new pond or making up for poor filtration or bio maintenance.
These products are also ineffective if used in a pond with no filter or at least gravel bottom for a place to accumulate these bacteria/enzymes. For example, dumping these products into a bare fountain/pond that only contains a pump for circulation will result in little effectiveness.
While on the subject biological nitrogen cycle, I should note that many pond filters are only designed to perform aerobic nitrification which is certainly very important, but only removes ammonia and nitrates. The removal of nitrates is only performed by direct use by plants and their roots or be de-nitrification. For this reason the use of products such as SeaChem Pond Matrix inside filters or for use in potted pond plants (with pond rocks placed on top to keep the very light Matrix from floating).
Algone is a product I have used for many years now with my aquarium and pond maintenance company for water clarity, nitrate control, and as a part of string/mat algae control regimen.
Algone utilizes nitrate fixating microorganisms that incorporate excess nitrogen into the cellular mass, while bioactive enzymes assimilate nitrogen from the water column.
Another before mentioned product that aids in natural water quality and clarity is Barley with Peat as this combines peat with the benefits of barley straw. The phenolic compounds found in the Barley naturally clears the pond while the peat contained in buffers the pH for a more stable pond environment.
The use of these two products can have the end result of lower algae growth (including green water) and over all improved water clarity.
I have found best results with ANY bio pond care products when added in the evening and if a UV Sterilizer is attached to the pond, turning this off for the evening and then back on in the morning (when the need for a UV Sterilizer/clarifier is highest), allows the bacteria/enzymes a better chance of getting into substrate and filter media where they will be most effective in digesting organic sludge and waste. When organic decomposition is higher and more time is needed for products such as Stability to work, I would again suggest turning off the UV in the evening, adding the Stability or similar product, then leaving the UV off for the first two nights and one day; then turning the UV Sterilizer back on the second morning.
 POND FOAM:
Foam around waterfalls and other water features is not uncommon, however if this is a persistent problem, there may be other issues at play in your pond. Often this is caused by too many organics, so lowering you bio load, watching the amount of food you feed and most importantly; improving filtration can go a long way here.
This can also be caused by an excess of Phosphates (often related to organics in the water column already mentioned). Phosphates can be added from tap water or even more often, runoff from watering or rain water through your garden. For this make sure your pond has a raised ledge to prevent this problem (I talk about this further under Pond Bottoms).
For minor problems, especially foam that occurs only around water features, products such as Jungles No More Foam can be useful for blocking the waters ability to foam.
 POND CHEMISTRY (GH, KH, etc..);
This is important not just for fish health, but also for algae control as well. Besides ammonia, nitrites, and phosphates kept near 0 ppm, nitrates should be kept under 50 and the often forgotten GH and KH should be kept no lower than 100 and 50 ppm respectively.
A good electrolyte level maintained by a proper GH will also help maintain a good Redox which in turn aids in water clarity, not to mention the very important aspect of good osmotic function in fish for long term health.
If your GH is low this can be a problem (with a stable pH) during the hours of the day when photosynthesis is high, even with an adequate KH.
It is possible in a pond with heavy plant growth and/or high algae growth without adequate water hardness (GH), for aquarium chemistry to become problematic due to increased photosynthesis. So either the reduction of algae and/or an increase in minerals to aid GH is important if GH, pH, or KH are problematic.
Products such as Wonder Shells can help with supplying essential mineral cations (as well as stress from transfer and poor osmoregulation)
please click the picture to enlarge for better view
For more about how this affects algae, please follow this article:
For more about Alkalinity and hardness in ponds, please read this outside resource:
Interactions of pH, Carbon Dioxide, Alkalinity and Hardness in Fish Ponds
I recommend reading “Calcium & Electrolytes in Aquariums (and Ponds)” for more about this aspect of chemistry or “Proper Osmotic Function” for the effect of electrolyte levels on fish.
Generally most Pond Fish such as Koi and Goldfish like a higher ph of about 7.8 (although a pH in the range of 6.8 to 8.0 is often acceptable). A well planted stable pond usually does not have problems with too high or too low a pH.
If your pH is too low/unstable, Sea Chem Buffer can improve the stability. For large volumes of water, aragonite may be more cost effective (Oyster shells are too slow to dissolve and do not work well IMO). However I do NOT recommend the use of Plaster of Paris or lime (CaO) as this is not balanced and not add the other necessary elements such as Magnesium, carbonates.
For too high a pH (rare), these are cost effective ways in a pond:
*Barley Straw pellets or extract (great for algae control too, although so-so for ph)
*Almond shells (this is really good for lowering ph, more effective than peat and with the side effect of being antibacterial)
*A veggie filter (this helps with a stable pH and produces nitric acid).
Feeding a quality diet can be beneficial for growth, breeding, color, and even the environment as there is less nitrogenous waste to add to the water column.
You want a food high in aquatic based proteins (although not too high in protein as most koi and goldfish are more “grazers”). Whole fish meal or white fish meal is a good source. An amino acid that is important to koi and goldfish is DL-methionine and is found in Whole fish meal as well as peas.
Cereal is not a good source of energy for fish as it is in humans, fish utilize fats more for energy. Cereal is mostly used as roughage and to move other nutrients thru the digestive tract.
In summer months I usually feed twice per day, as temperatures fall below 70 F (20 C) in the pond I feed once per day. When temperatures fall below 60 F (15 C) in the pond I feed every other day or less, depending on fish feeding habits. Below 50 F (10 C), I do not generally feed.
For adult Koi there are several quality foods available: Hai Feng, Sanyu, A-Zoo, Hikari, and Nursery-Pro as well as "super premium" brands such as Aqua Masters just to name a few. For goldfish or shubunkins I recommend Spirulina 20 Flake, Hikari, or Sanyu. For fry (in addition to natural foods that will be available around the plant roots and other calm areas of the pond), I powder Spirulina Flakes and stir it into a cup of water, then pour this solution into the area the fish fry are at.
For even more information about what constitutes a quality fish food and more, please visit this URL: Quality fish Food; what ingredients are needed for proper fish nutrition, health and growth.
This is a broad subject that is beyond the scope of this article, so I would suggest reading more specific articles, here are a few suggestions:
*How Medications Work; Both Pond or Aquarium
*Disease Prevention; Aquarium AND Pond
*Ich; Treatment, Prevention, Lifecycle
This is far a complete list, however many more can found in our Aquatic Information drop down list in the header bar or at Aquarium/Pond Answers.
One important point I will make that is not pointed out in these articles as although this is important for aquariums, it is much more important for ponds, and that is the importance of changing water (at least 25%) prior to every single treatment.
The reason is that ponds in particular generally have a high content of dissolved organics, floating algae or similar bio substances, much more so than the average aquarium. These organics will absorb many treatments, especially chemical treatments such as those that contain Malachite Green (such as Quick Cure, which is a very effective pond treatment of many small pond parasites).
By changing water first, this allows for more medications to be delivered to the pathogens causing disease, as well this will generally improve water conditions which in turn helps the fish fight off the infections/infestation better. This can also lower the amount of medication that might be needed to treat your pond as well.
I recommend this water change prior to any and all treatments.
 WINTER POND CARE;
It is important in winter to keep at least a small section of your pond open for proper exchange of gasses (O2, CO2), if water can still flow into the pond through a water or aeration device, that will work. A minimum depth of 24” (deeper in climates where soil temperatures drop below 32 F) will provide enough water space under the ice for fish to hibernate (even in the coldest climates, ice will really extend more than 6-8”). However if you live in an area of hard freezes, you may need heaters or a device such as this Pond Master Deicer:
If an aquarium heater is adapted to your pond, make sure that there is circulation near the heater and keep in mind that all you are attempting to do is raise the temperature above freezing, so generally only about 1/2 watt per gallon is all that is necessary for most ponds to keep above freezing (assuming adequate circulation). For example, a 300 gallon heater should work for most 600 gallon winter ponds (unless you live in the arctic circle)
An aeration device or pump placed about midway from the surface/bottom that circulates upward generally will keep an area of the pond surface free of ice and allow proper gas exchange. In deep ponds over 5-6 feet (1.75 -2 meters), thermal layering, called thermoclines, may exist. This acts as sort of an “inversion layer” similar to how smog gets trapped in the air in Los Angeles. This traps CO2 and Hydrogen Sulfide near the bottom which is dangerous to fish and in this case you need to add water pumps or aeration devices at the bottom.
Here is an example of a simple aeration method using an air pump and air stone (click to enlarge).
You can also connect an Air Pump to air driven Pond Filters such as the Hydro Pond II for added winter filtration (especially if your main water pump is shut off).
If you live in an area where leaves fall (even if there is no winter ice), removal of these leaves or covering of your pond is a necessity to prevent decay that will produce ammonia, CO2, nitric acid (which in turn lowers pH and KH to dangerously low levels).
Decay can also result in the production of Hydrogen Sulfide from anaerobic breakdown.
Sometimes removal of fish in the winter is also necessary when the pond is very shallow (under 18-24 inches). I recommend avoiding this if at all possible with larger mature fish as this can injure and often cause more stress than simply improving your pond to deal with winter conditions.
If this must be done with younger fish, you need to find a tub that is as large as possible (the tub pictured at the left or a plastic untreated livestock trough works well as well as sturdy "Kiddie pools").
I recommend using a simple pond filter such as the Hydro Pond II connected to an air pump to filter such a tub pond. Keep the pond in an area of your garage or similar that is above freezing but not too warm so as to minimize activity and need for feeding and thus pollution.
Generally UV Sterilization does not need to be run in climates where hard freezes are common; however once most hard freezes are past (ice forming on the surface of the pond), UV Sterilization should be run again.
As long as circulation is good and overall water temperature is above freezing there is no danger to your UV Sterilizer/Clarifier. It is noteworthy that as your pond temperature increases your UV will become more effective, but then so does your potential for algae blooms.
Here is a good article about Winter Pond Care:
“Winter Pond Care”
 POND BOTTOM, CONSTRUCTION, REPAIR, SUBSTRATE:
Construction and make up of your pond can be done in three different ways (and there is no one best way; the best way fits your pond size needs, climate and budget).
A preformed pond is probably the most simple. With this method you basically dig a hole to the shape of the pond, remove sharp rocks, add sand for a cushion maybe cut a few holes on the size for bulk heads to add filtration and you're ready to add rocks, filtration and décor. This style is good for small applications (usually under 250 gallons) and where roots or gophers may be a problem.
A pond liner made of PVC material or EPDM. I prefer the EPDM in a 45 mil. Thickness.
With liners you can generally go up to a 1000 gallon pond. Preparation is similar to a preformed pond, however more care needs to taken with sharp rocks and a pre liner or sand should be used. Also in areas of high tree roots or gopher activity these can be compromised.
The other method is a concrete pond using rebar for support as well. This is probably the most expensive method however this is the method I recommend over 1000 gallons. I have subcontracted (installing the filtration) for many concrete ponds and it is important to use a good contractor or prepare and build this properly yourself as even a concrete pond that is poorly built can have problems. Make sure to not build a concrete pond on “fill” as the pond will often settle and crack. Also proper use of rebar is a must especially in ponds over 3000 gallons.
Despite the popularity of drains, I do not install these as I prefer to allow the aerobic and anaerobic bacteria breakdown wastes (I will have a PVC T and ball valve near an outside filter to drain my pond via my pump for water changes and cleanings).
It is not unusual for a pond to have a leak from either time, poor construction, weather damage, animal damage or "you name it".
I would recommend products such as Pond Pro 2000 which are a liquid version of EPDM basically the same as EPDM pond liners sold in pond supply stores. This product is a 100% liquid EPDM and 100% compatible to your EPDM pond liner sold in pond supply stores.
This type of product also works extremely well on all non-porous concrete ponds & fountains as well as EPDM fish ponds liners & prefabricated ponds.
(This website is not affiliated in any way with Pond Pro 2000, I/we only feel it is a very useful product and this article would not be complete without mentioning it or similar products).
Rock or large gravel on the bottom will aid in the growth of bacteria to break down organic matter.
In smaller ponds (under 200 gallons) I personally usually do not add a substrate per say, rather I allow the roots of potted plants (that will grow out of there pots) to collect there own debris. I do often add some zeolite or laterite both for absorption of some nutrients and for plant roots.
Drainage problems around your pond:
If you are having flooding problems around your pond, you may need to dig a trench to lay PVC drainage lines to an area of your property that is lower. If this is not possible, a dry well may need to be installed. This article deals with building a dry well: Better Yard Drainage.
Garden/ Yard Drain with clean out and basic drain.
 SPRING FED POND (Also water level maintenance);
If you live in an area of natural springs or have creek flowing nearby, this can make for a very healthy, clear and natural pond. If it is possible to divert water into your pond (or just fill from below with a spring), this is always an excellent idea! This way you will likely maintain lower nitrates and phosphates, less algae, better Redox, and better electrolyte levels resulting in a clearer pond and healthier fish. Make sure to have an overflow or skimmer to remove excess water. If you have a well you can achieve similar results (or even use your well during the dry season when the spring or creek diversion dries up).
I also have achieved a similar effect with just plain tap water used in a very slow flow (a 10% water exchange per day or less will not show any ill effects from chlorine). Make sure this is not a problem with local water companies first, although the ponds I used tap water overflow on used less than 200 gallons per day (for a 2000 gallon pond) which is less than watering ones lawn for an hour.
If with this method, filtration and circulation are still needed in my experience, although this often allows for a more simple filter (such the Hydro-Pond Sponge Filter). A Veggie filter is very useful in this set-up too!
Another method for adding water simply is a float valve. These will add water due to evaporation or loss of water by other means and can even be used with flow through system to automatically regulate water level. Here is a picture of such a float valve by Hagen (Laguna).
Reference: Ground Water
 KOI, GOLDFISH, ROSY-RED FATHEADS & GOLDEN/BLUE ORFE;
Koi, Orfe and Goldfish are all from the family Cyprinidae.
Koi can grow very large, up to three feet (the Butterfly variety does not grow as large in my experience). Koi are ideally kept in at least 200 gallons per fish (I have kept them in less however this is less than ideal). On the other hand can grow up to 23” (I find this somewhat uncommon though) and are better suited for ponds under 1000 gallons and especially ponds under 200 gallons. This site also has some good articles about Koi: KoiVet
Shubunkins are a very inexpensive yet very pretty goldfish that have many color variations like koi, however these do well in small ponds.
The Golden Orfe (& Blue), is suitable for ponds. It can grow up to 2.5 feet but usually stays near 1.5 feet. It is a long, slender, bullet-shaped, schooling, orange fish often with black dots on its head and back. Orfes are native to Europe and were derived from the ide which is a silver predator. They need lots of room generally live 10 20 years, however this has not been established.
They are great to put goldfish and koi at ease and encourage them to spend time near the surface. Many pond keepers say that Golden Orfes are better pond fish than goldfish. This is probably due to their fast, active behavior near the surface where you can see them seemingly having fun.
The Fathead Minnow and Rosy Red Minnow are popular fish for ponds and even aquariums. These small graceful fish do well in similar water conditions as Koi, Goldfish, and Orfe which is higher GH and a pH between 7-8, and prefer temperatures between 50 75 (10-24 C), although they can survive between 33- 100 (1- 38 C).
Fathead minnows grow to 2-3 inches (5-8 cm.) for males and 1-2 inches (3-5 cm.) for females (which can be identified by Ovipositors, fatter and shorter bodies).
These are generally peaceful fish with breeding habits similar to Cichlids and often will “stir up” Koi and other larger fish to make them come out more and are less cautious.
Fathead Minnows will eat most offering and will do well with what most goldfish or koi eat, although they tend to be a bit more carnivorous, and will eat a lot more mosquito larvae and similar (these are excellent to keep down Mosquitoes). Kept in an aquarium I would recommend tropical fish food due to their more carnivorous needs.
For more information about medications/treatments, please visit Aquarium (& Pond) medications and Treatments
 POND PREDATORS:
Herons have been the most common predator to my customers ponds that I have had to deal with. I do not like to add anything that detracts from the beauty of the ponds I maintained, so decoys were my first choice.
I found Heron decoys such as this one by Hagen: worked well at not only scaring away Herons, but other predatory birds as well such as Cormorants, Owls, etc.. (I might note that these decoys do NOT work in breeding season which early March 'til late May where they actually may attract Herons!). I also suggest moving the decoy around as Herons can quickly learn that this is a fake Heron.
I also employed motion sensor scarecrows that connected to a water supply and then squirted ANYTHING that moved (such as other predatory birds such as Owls), this device also worked for dogs that would “play” in the pond (often destroying it and scaring fish), but was not as effective for raccoons.
This Alligator decoy is another Heron deterrent that others have used successfully (I have not used this method myself, so I cannot personally vouch for it, but it certainly seems like a good idea and I trust those who have claimed to use it successfully).
Another way to protect your fish from predators is a 12” diameter drain pipe placed (and hidden) under water for the fish to escape and hide in.
One more idea is under water fish decoys combined with the drain pipe or similar methods. These ‘fake’ koi give the real fish time to escape (these last two suggestions have worked for me, but not in all cases).
I do NOT recommend wire mesh as some other sites suggest as this is very ineffective and just plain UGLY (why would you make a beautiful garden pond just to cover it in wire?).
I have seen raccoons and even Herons find a loose spot and go right under.
The only time I would recommend wire mesh or netting is in fall to stop leaf litters which can often over come a ponds bio capacity. Maples can especially be bad about ruining an otherwise healthy pond.
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