There is a plethora of filter products designed for use in ornamental ponds. There are so many choices available that it can, in fact, make the job of choosing a filter more difficult for the consumer. We spend a great amount of time testing filters and determining their usefulness, if any, in the pond.

Manufacturer claims are often over-glorified as to what the product can actually do. For example, the manufacturer may claim on his label that his “biological filter” is “effective for ponds up to 1000 gallons” when, in reality, his product is only a piece of padding that fits over the intake of a submersible pump which is a pre-filter, not a biological filter. He gets away with what we consider a misrepresentation of his product because there are no standard guidelines for what equates to a biological filter — and — what it is effective against. Does it claim to clear the water? Clean the water? Make it biologically healthy for pond life?

To throw a monkey-wrench into the decision process of choosing a filter, the amount of gallons a filter can effectively filter is subjective to the circumstances of the pond. A 1000-gallon pond that is primarily a water garden with only a few goldfish would need less biological filtration than a pond of the same size that is home to more than a dozen larger-growing koi. When we rate the effectiveness of a biological filter by number of gallons we are taking for granted that the pond has a normal fish load which we calculate to be about a dozen koi in 1000 gallons of water. There are more factors that exist that can skew our “normal fish load” such as how much and how often the fish are fed.

Types of Manufactured Filters

There are basically three types of filters available on the market that are capable of offering mechanical and/or biological filtration. Though many of the types of filters provide both mechanical and biological filtration they do not provide the same quality. The type of filter (or types of filters) you decide that you need for your pond should be determined by what you need from your pond. If it’s koi you’re raising you’ll need the best combination of biological and mechanical filtration you can get. If it’s more of a water garden you’ll want to opt for a filter that rates high in mechanical filtration.

Manufactured filters fall under one of three categories:

Open System / Closed System / or Pre-Filter

The Misunderstood Pre-Filter

The pre-filter’s job is necessary because it protects the intake of the submersible pump from large debris in the water so the pump will not clog or clog as easily. No pond should be without one. A pre-filter, such as the basket on a skimmer, the box surrounding the pump, or the screen that attaches to the intake of a pump, traps leaves and other large debris when water passes through it. Another fine example of a pre-filter is the leaf basket that is attached to the intake of an external pump. Because it removes debris it is considered a form or mechanical filtration.

Shame on those manufacturers who call their pre-filter a biological filter. They wrap the basket or screen with sponge or another type of filtering material and then, suddenly — ta-da! — it’s magically converted into a bio-filter. That little piece of material’s going to do nothing but clog up with small debris.

We don’t suggest using material around the pre-filter screen in most applications for the simple reason that the material traps smaller particles, clogging the pre-filter quickly and causing more cleanings than necessary. One of our biggest complaints is when people are forced to clean this material everyday because the pump cannot pull water through all the built-up solids and stops pumping or pumps with severely limited flow. To make matters worse, a vicious cycle occurs every time the filter is cleaned. Whenever this material is moved the dirt that was trapped is released back into the water causing a puffy brown cloud of dirt which, in turn, makes the water murky until the dirt once again gets trapped by the filter.

Filtering the Small Pond Or Water Garden

A small pond primarily used as a water garden has less need for biological filtration than a fish pond. If no filter is installed other than perhaps a pre-filter and the pond holds only a few fish (2 or 3 tops!) the fish will be moderately safe but the water will be dirty brown in color and not very attractive. If crystal clear and healthy water is desired ponds larger than 300 gallons will need the mechanical filtration abilities of the smallest bead filter. A pond less than 300 gallons may get by with less expensive filters that will provide some mechanical and biological filtration. It all depends on the fish load. We’ve listed our favorite choices for ponds that fit into this category. The PondMasterÔ is our choice for water gardens with very light fish loads. We would opt for the Ocean ClearÔ if the pond contains more than a couple of fish or is loaded with messy plant material.

The PondMaster is a square filter box that contains two filter pads and attaches to the intake of a pump by a tube. PondMasterÔ kits are available that include the filter, pump and fountain attachment with both fleur-de-lis and bell spray heads.

We’ve found very few submerged filters we consider more than pre-filters. The PondMaster does a fairly good job of removing solids and handling light biological filtration for small water gardens with light fish loads.

This filter, when purchased as a kit, is a great kit with which the beginner can, pardon the pun, get his hands wet. It’s simple to install, everything needed is included in the kit and, because it’s submerged, is hidden from view.

Cleaning can be a chore. The handle on the filter makes it easier to lift out of the water but opening the top can be a bit aggravating. A drawback from this type of filter is that when you lift the unit out of the water some of the dirt that has been trapped in the filter material leaches back out into the water.

One of the best features of this filter kit is that it goes easy on the pocketbook. The pads must be replaced every year but there are only two of them. We keep this filter and kit in stock at all times because we’ve found that it is a reliable and easy to operate system for the new (or veteran) water gardener who only wants a small water feature and possibly a few goldfish.

The Ocean ClearÔ Filter is one of the most popular canister filters on the market. It has excellent biological filtration for its size and, with the proper media, it can be an excellent mechanical filter as well. We suggest this filter to be used on small ponds that have normal fish loads. It makes a great quarantine or hospital tank filter.

The Ocean ClearÔ is a closed, air-tight canister that is filled with different types of filter media, the choice of which varies by retailer. We choose to use round discs of varying textures as the filter material inside the unit. Rings in the middle of these discs pop out so that other types of media (such as oyster shell) can be placed inside.

Because it is a closed-system the filter can be placed practically anywhere as long as the pump is strong enough to carry the water to the unit and back to the pond. It can be submerged in the pond to hide it or the unit is small enough that it can be easily stashed behind a waterfall or plant.

Installation is quick as long as the fittings are correctly sized to the rest of the system. If the filter is not submerged it is also not a hard filter to clean. The top screws off and allows access to the filter media inside so one can easily wash the pads with the hose.

This filter is similar in cost to the PondMasterÔ kit but the Ocean ClearÔ doesn’t include the pump or fountain attachments. The pads inside the unit flatten with use and must be replaced once a season which adds a bit more cost to the filter. The tank itself should hold up for many years.

This is one of our favorite filters for use in small ponds with a normal fish load where clean, healthy water is desired.

Closed Filter Systems

A closed filter system is any filter that is contained in a single water-tight canister or tank. We strongly advise against trying to open these types of filters while the pump is running — unless you happen to like strong blasts of water hitting you in the face!

Advantages of the Closed Filter System:

Because they are water-tight they are portable. As long as the pump is strong enough to push the water you can place these filters anywhere you choose to put them. Most kinds of closed filter systems are strong in mechanical filtration abilities. They tend to be easily installed and a large number of them are compact and easily hidden.

Disadvantages of the Closed-System Filter

Because they are water-tight they do not allow as much opportunity for the introduction of oxygen. Less dissolved oxygen in the water means the closed-system may not be as fertile an environment for bacterial growth as an open-system might be. This does not mean that they are not good providers of biological filtration. Some are better than others.

Canister Filters are considered closed-system filters. They contain a reasonable amount of filtering material and rely on the power of the pump to continually circulate water through them. A canister filter must be taken apart to be cleaned.

A good example of the canister filter is the Ocean Clear which is further explored on page 7.

The Bead filter is perhaps our favorite closed-system filter. It’s filled with thousands of beads (not sand) where even the tiniest particles get trapped. It relies on water pressure generated by the pump during backwashing to jostle the beads and release the solids so they can be cleansed away. It’s the best mechanical filtration available, often cleaning so well that the pH must be monitored. A bead filter can double as an effective method of biological filtration. The beads are backwashed with pond water so there’s no chlorine to affect the life of the bacteria that colonize on the surface area of the beads.

Installation of a bead filter requires a (very) basic knowledge of plumbing and is basically a snap. The modern bead filter is truly the easiest of all filters to clean. With a turn of the handle it backwashes, rinses and starts filtering again. It takes only 5 minutes per week to backwash the unit — then once a year it takes about half an hour to perform a power backwash. One does not even get his hands wet during the process.

The investment in a bead filter is all up front. There is no expensive media to replace each year. Units range from $525 to over $1000, depending on the capacity of the filter. When you calculate the money saved on replacement media over the course of a couple of years by the time you save cleaning each week, it makes good dollars and cents as well as sense to purchase a bead filter.

Unlike modern state-of-the-art bead filters, the BubbleBeadä does not use the pump’s water pressure to backwash its beads. Instead it relies on a gravity system that isn’t as powerful and, in turn, does not perform cleaning functions as well as its counterparts. When solids are not properly removed from the filter the beads cake together and cause the filter to clog. This happens most often during times of high algae growth and with ponds that are heavily planted. It’s this flaw in the design of the BubbleBeadä that contributes to its low marks in mechanical filtration.

The molded plastic of the tank is thin and not warranted to withstand water pressure of more than 15 psi. It has been known to burst from the pressure of high-performance pumps like those used for large waterfalls. Tanks on the newer bead filters are designed to withstand water pressure of up to 50 psi, allowing high-pressure backwashes that clean the beads more thoroughly. Because of this our choice of pumps that can be used with this filter is limited to low-head (pressure) pumps.

To insure proper cleaning of this unit one must occasionally take it apart and stir the beads with a stick to unclog them. That blows away any chance of it getting high marks for ease of cleaning. The tanks are not as compact as those of its competitors’ and harder to hide.

We respect the BubbleBead’s place in the history of bead technology. We would, however, like to see improvements made on the tanks. We cannot, in good faith, recommend this brand of bead filter over any of the others when you consider the fact that the others do not have these design flaws and are priced about the same.

Now that we’ve covered which bead filter NOT to purchase, let’s explore the bead filter that offers the best in bead technology for the least amount of cash!

Allow me to interrupt for just one moment…

I take my job as Editor very serious. Unlike today’s newspapers and news on television I still think that “the press” has a responsibility to its readers to tell the truth and not slant information for personal gain. Here, I’m “the press” and it bothers me that you might think I’m favoring the ProBead™ because it is manufactured by us. Yes. It’s true that I want to sell more of them but our sells are good enough that I don’t have to sell out to sell product. If our filter was manufactured by another company I would still push this product.

While others in the industry were busy selling their bead filters The Doc was busy testing and studying the design of popular state-of-the-art filters. He then took the best parts of each and rolled them into one. Wha-lah! In late 1997 the ProBead™ was born.

Initially, The Doc’s intention was to build a bead filter that provided greater flow rates while maintaining maximum filtration capabilities. Price of the filter was of no consequence. What he ended up with was a bead filter that is as good as the best and better than most that competes with the “big boys” at a “little boy” price. His ProBead™ turned out to be just as good as Koi Camp’s Aquadyne™ and Fluid Art’s HydraBead™, both giants in the world of bead technology with one exception. He feels he accomplished what he first set out to do by improving flow rates without compromising the bead filter’s extremely fine filtration capabilities.

The ProBead™and ProBead™Ultra High Flow Series of bead filters are manufactured by The Doc himself at our Alpharetta store. They are sold mainly to local customers and increasingly by mail order through our website on the internet. The smaller ProBead™is designed for small to medium-sized ponds and comes in 3 sizes. The ProBead™ Ultra High Flow Series are tan-colored split-tanks that are recommended for larger ponds.

Like other state-of-the-art bead filters, the ProBead’s biological filtering capability can handle normal fish loads but it’s still not quite as good as that of the vortex, an open-system filter. The bead filter, however, has the advantage of a 6-way valve that can direct the water flow so the filter can be by-passed during times when the pond is being treated for bacterial problems. Medicines that treat bacterial-related infections in fish (ulcer disease, mouth rot, fin rot, BGD, etc.) do not discriminate between good and bad bacteria and will wipe out a hard-earned colony of nitrifying bacteria in no time! This by-pass makes it easy to protect the bacteria.

We’d be lying if we said our ProBead™ is the BEST bead filter on the market and anyone who states that their bead filter is better than ours is - how can we put this delicately? - telling you a whopper. The truth is there’s very little difference in the design of the leading modern bead filters! The difference, then, has to fall on the price.

The price is what sets the ProBead™ apart from the others and it’s by NO SMALL MARGIN.

We really had no idea how the ProBead™ ranked in price with other bead filters of its kind. While conducting research for this edition of What’s Up, Doc? we were literally astounded by just how much lower the ProBead™ is in price than its contemporaries. Instead of raising the price because “we can get away with it” we chose to brag about it instead!

I imagine the reason why we can sell our product so low is because we manufacture it here. It costs us no more in overhead than we’re already spending. We don’t sell it through a distributor so there’s no “tack-on” for the middleman. We’re not big on fancy labeling so that cost is saved.

Do Not Install a Sand Filter to Do the Job of a Bead Filter.

Although they look exactly alike on the outside the two filters are far from the same on the inside. Sand, no matter how coarse, will clog and clog quickly. The plumbing is different too. Water flow is highly restricted in the sand filter. This will cause deadly conditions, encouraging the growth of parasites and anaerobic bacteria. The Doc installed a specially designed sand filter behind one of our ProBeads that was intended to serve as a water polisher by filtering out even tinier particles from the water. This experiment did not work. He is presently trying something different with it. We’ll see how it turns out.

Open-System Filters

An open-system filter is a container that is placed outside the pond designed so that water is continually filtered as it runs through material such as brushes or pads. Water enters from one side and goes out the other or it may enter the bottom and flow over the top. The greatest amount of mechanical filtration occurs where the water enters the unit. The material closest to this opening must be cleaned often. The material furthest away from this opening should be reserved for biological development and cleaned (or replaced) only once or twice a year. The unit is not air-tight allowing removal of the lid while the pump is running.

Advantages of the open-system filter:

The open-system filter has the overall best rating for biological filtration only when it combines an oxygen-enriched environment with plenty of filter media to house and nurture bacteria. Some manufactured open-system filters, especially the smaller ones, fall short of the required amount of filter media while other filters offer a virtual “smorgasbord” to tempt the growing bacteria. It’s potential for excellent biological filtering can be helped along by dropping an air-stone between the folds of the filter material, enriching the amount of dissolved oxygen in the water. It would be impossible to do this with a closed-system.

Disadvantages of the open-system filter:

Solids will accumulate on the bottom of these types of filters and, unless it’s been fitted with a means of easy removal such as a bottom drain, all the material in the unit must be removed in order to clean the solids out. Care must be taken when selecting and installing a pump. If the water is pumped through too quickly the unit will overflow. You don’t have the same flexibility of where you can place the filter as you do with closed-system filters. Each design constitutes where the filter needs to be, whether it works best placed higher or lower than water level or how far away from the pond the filter can be placed.

Blending this style of filter into the landscape may take some thought. Small boxes are easily hidden within the waterfall but that won’t work for the larger, more biologically effective filter units. Installation time ranges from an hour to a couple of days and the difficulty of installation from quite simple to “hire a consultant”. It should be noted that large open filter systems are extremely difficult and may take the longest time to install.

How easy it is to clean a gravity-fed filter depends on how it was constructed. The worse offenders are the ones that require you to remove all the material to get to the media that needs to be cleaned. The time it takes to clean the filter each week varies from half an hour to a whole afternoon, depending on the filter itself. It’s awkward to handle huge pads and there is at least one large filter with which we’re familiar that utilizes them. Open-system filters that rate high in mechanical filtration make use of settlement chambers. These tend to be easier to clean if a drain is placed so that solids are drained out from the bottom and discarded.

The cost is fairly inexpensive for small units but it’s necessary to factor in the cost of replacement media that must be changed every year. A medium-sized gravity-fed system can end up costing more than it’s bead filter counterpart but provides a little more bio-filtration. Large filters of this kind tend to be extremely expensive.

The small box filter can be very effective for small to medium-sized ponds with a normal fish load. The amount and types of filter materials used can mean life or death for its mechanical filtration abilities and its bio-effectiveness.

There are several examples of these types of filters available on the market.

Our choices would be products that have the following credentials:

The box should be big enough. We wouldn’t want anything less than the size of a letter storage box. Bigger boxes mean more room for more media.
Enough filter material. The box should literally be filled with filtering media. The more the better.
The right kinds of media. Some media is used to take solids out while others store and promote the growth of nitrifying bacteria.
Easy access to material used for mechanical filtration. You should never have to dig for the media that filters the solids in order to clean it. Make sure the water enters through the top pads or from the side if you can easily slide the side material out.
Bigger openings for water to flow out than in. The flow of water entering the filter cannot be faster than the flow leaving the filter lest the filter overflows.

The retail cost of a small quality filter box with mechanical and biological media included should be between $150 and $200. I would question the effectiveness of any box filter that costs less.

The large box filter works basically the same as the small box filter but on a larger scale. Only a few people build this type of filter (often specially built per order) and I’ve never seen a brand name for one. It is truly a highly effective biological filter. There’s plenty of material where bacteria can feel free to colonize. It’s an open system so oxygen is easily introduced into the growing environment.

The filter material used most often are large panels of commercially-sold filter media that trap debris as water flows through. It does a fair job of removing solids but cleaning those solids out later can be a nightmare.

It’s not easily installed and cannot be placed just anywhere. Installation consultation is available for a hefty fee from the person who built it. This filter box cannot be hidden in the waterfall! The giant unit takes up a great portion of space. Often times privacy fences are constructed around it to successfully blend it into the landscape. I’ve seen one creative example of bamboo panels surrounding it in an oriental garden.

If you prefer to spend your Sunday afternoon cleaning the pond filter then this one’s for you! It takes the better part of the day to clean this filter — and during pond season this must be done every week. It’s not suited for the wimp (like me). Large pads when water-soaked are heavy and hard to manage.

So, how much would you think a filter that gives “good bacteria” but works you to death costs? More than I would ever want to pay. This kind of filter has the reputation of being ultra expensive and, as I mentioned earlier, consultation alone can run into the thousands.

If you already have this type of filter installed and regret having ever bought it in the first place — don’t rip it out just yet. Your investment doesn’t have to be wasted. A properly-sized bead filter installed before the large box filter will trap the solids and allow easy weekly cleanings. This will allow you to limit the number of times you must clean the large filter box to once or twice a year.

The “How Not to Build a Pond” Kit is a system commonly installed by landscapers that comes pre-packaged with everything the landscaper needs for installation including a video on how to install it.

The design of system is quite simple. Water is taken off the surface of the pond by way of a side skimmer. The submersible pump is in the bottom of the skimmer housing and pulls the water through a pre-filter before it is returned to the pond via a preformed waterfall that the manufacturer calls a bio-filter (which is their version of a type of open system filter). When installed correctly it produces a very pretty water garden.

Even though this system can make a pretty water garden in our opinion it DOES NOT have what it takes to make a healthy pond environment for fish. Since all the water is drawn off the top by the side skimmer, the water on the bottom is not circulated and could become anaerobic. To make matters worse the manufacturer instructs the installer to line the bottom of the pond with rock. Water that is not circulated combined with a year or two of solids accumulating in the crevices of the rocks on the bottom of the pond is a recipe fish health problems.

The biological filtration of this system is contained within a plastic waterfall unit which acts similar to a small box filter. It only contains 3 or 4 pieces of filter media which is, in our opinion, not enough for it to be an effective biological filter for medium to heavily stocked fish ponds.

Installation is not easy, even with the help of an enclosed video. You need the tools of a professional to excavate the pond site correctly and leveling and placement of the different units can be difficult.

The only advantage this system has going for it is its ability to blend in with the landscape. Everything is buried and the pump is submerged.

Cleaning the material in the waterfall is like cleaning a small box filter. The pads are removed and cleaned then replaced. It’s not the easiest kind of filter to clean but it’s not the hardest either.

One of our biggest concerns with this choice of “filtration” is the lack of… Another major concern is the skimmer on this system. It is designed like a swimming pool skimmer and, though the manufacturers may tell you that it’s not harmful, it certainly is! Fish meet their demise by following floating pellets of food into the skimmer and they are not able to get back out.

We were hoping that, with all its problems, the price for this kit would be reasonable. We compared it to the retail cost of installing a bead filter system complete with bottom drain, fish-safe skimmer and external energy-saving pump. The cost of the kit is actually higher! No value for the buck here! You can build a beautiful fish-safe, easy-to-clean, easier to install fish pond for LESS than using this kit to build a water garden that is harder to clean, harder to install and not as safe for fish.

As a retailer of water garden supplies we can stock any type of filters we choose. We choose NOT to stock this one. We can order these systems and have them available with just a few days notice. We have sold them (reluctantly) to those who insist.

For years this product has been the preferred pond kit of landscapers so I can only guess that millions of these kits have been installed. What made us really take a look at this product is the sheer numbers of people who have this system and have sought help from us with recurring fish health problems.

In a nutshell, if you want to spend more money than you have to for a product that creates an attractive cess pool — I’ll be happy to special order one for you.

A favorite for years in England this system has become popular among koi enthusiasts in the United States for it’s outstanding biological and mechanical filtering capabilities.

The vortex is a series of cone-shaped tanks, usually 3 of them, that put all the principles of filtration to work. Water is fed by gravity into the first tank where it slowly swirls. The gentle “vortex” of water encourages solids to settle to the bottom of the tank where they can be discarded during the weekly cleaning. This mechanically cleaned water is continually pulled by gravity into the second tank that is usually loaded with brushes where more mechanical filtration occurs. Then the water travels to the third tank that is filled with another form of filter media such as ribbons. This third cone is where the biological filtration lives. A pump is at the end of the filter system and pushes the water back up to the waterfall, pond or stream where the cycle begins all over again.

The vortex is an excellent mechanical filter though not quite as good as a bead filter. The first and second cones are dedicated to removing solids. Drains at the bottom of each cone open to expel solids that have settled to the bottom, thus the cones of the vortex are considered settlement tanks.

Though brushes or pads in the second cone further filter the water mechanically they also provide biological filtration. The third cone, however, is reserved for the bulk of the biological load. We give this system 2-thumbs-up on both its mechanical and biological filtration abilities.

Wish we could say the same about installation of the system. The vortex system is truly one of the hardest filter systems to install because it takes careful planning as well as hard work to align the water levels and create the right amount of flow at each step. For example, the cones are placed so that the top of the cones are at the same level as the water level of the pond. Gravity pulls water through the bottom drain and into the first cone. It relies on a pump to move the water back up to the pond after filtration. If the water is pumped out faster than the first cone is filled by gravity the system will be pumped dry.

This system cannot be installed in just any backyard. The topography of the yard must have a severe drop off so one can install the cones so that they are level with the pond. You then need access to the bottom of the cones in order to open the drain valves for cleaning. These valves and the pump will be lower than the water level. There are several examples of successful installations where the cones were “planted” in flat land — buried so that the top of the cones were at water level. This required extensive digging and complicated the installation process tri-fold. We also do not like to bury these units because of problems that can arise later. Draining solids from the bottom is the magic to making this system perform. You can’t do this if the drain is underground. There are sophisticated ways around it but if something happened and one needed access to the drains it would present one huge problem.

Hiding the vortex system can be a bit of a challenge. The vortex is usually installed on larger koi ponds where its excellent biological filtration is necessary. The larger the pond the larger the cone. We’ve seen where folks have constructed “garden walls” of wood around them. There’s not much more you can do if these cones are placed where they can be seen.

They are not difficult to clean. All filter material can be simply shaken so that solids fall off and to the bottom to be drained away. A large vortex system may take about an hour and a half each week during pond season to maintain.

The vortex filter system is best suited for a full-fledged koi pond where powerful mechanical and biological filtration are absolutely necessary. There is sticker shock with this system. It easily costs twice as much as a bead filter for the same pond size. The trade off is better biological filtration. Some koi enthusiasts pay big prices for their koi and they feel like the high cost of this type of filtration system is nothing when it comes to protecting their investment.

This is a great filtration system and we would recommend it to anyone who has koi and can overcome the obstacles of installation presented by the system. It’s more expensive and harder to install than any other type of filter but - after it’s finally installed and up and running - the vortex rewards the homeowner with years of reliable, easy to manage, safe filtration and outstanding water quality.

Golden Rules of Filtration

When exploring filtration methods and comparing brands of available filters there are a few simple rules that one should always remember:

You can never have too much filtration.
If you can’t clean the filter you don’t need the filter.
High priced doesn’t necessarily mean high quality.
Natural filtration alone is not enough.
Labels lie.
Clear water isn’t necessarily healthy water.

cosmology