# How to Calculate Total Dynamic Head

Finding the right pump for a water feature can be a challenge, and the stakes are high. The right pump, delivering the right flow at the right head height, while at its Best Efficiency Range, will last and last. Specifying the wrong pump or plumbing can damage the pump, increase operating costs, shorten pump life and lead to pump failure, perhaps even a fish kill if the water feature happens to be a fish pond.

In order to properly size the pump for any water feature, you’ll need to know both components of the work it has to do, the flow and the pressure. The flow is the volume of water it can push in a given time, measured in gallons per hour (GPH). The pressure is the force required to push that flow through plumbing and up to the top of the water feature. We measure pressure in ‘feet of Head”, because it’s easy to visualize. A waterfall four feet high requires the flow be delivered at 4 feet of “Vertical Head”, plus the extra work required to push that flow through the plumbing, the “Friction Head”. The total pressure required is the “Total Dynamic Head” (TDH) of your water feature. Once you know the GPH and the TDH, you can plug them into the Comprehensive Pump Chart (Chart C) to find the right pump.

Follow the steps below to calculate TDH and find the perfect pump for your water feature.

## determine friction loss

#### FIND TUBING SIZE & FRICTION

Find the dark blue cell in the row that corresponds with the Recommended Flow (GPH) in the chart below. The column indicates the recommended tubing size and the number in the cell is the Friction Loss in every foot of tubing. Keep Friction Loss low for greatest flow.

To find the Friction Loss of existing systems, estimate the flow through the actual tubing size used.

#### Chart A

Add the equivalent lengths of all the fittings in the system from the chart below.

Multiply the Equivalent Tubing Length in feet by the Friction Loss in the dark blue cell from CHART A to find the Friction Head of the system.

#### FIND THE TOTAL DYNAMIC HEAD

Add the Friction Head in Feet to the Vertical Head of the system. Vertical Head is the height in feet from the surface of the water the pump will be TDH sitting in, to the highest point the water is pumped to.

Find the TDH at the top of CHART C, then find the pumps below that provide at least the Recommended Flow. Grey colored cells indicate that the TDH is outside the pump’s operating range and the pump will likely not last in this application. The light blue cells indicate the pump is operating within its operating range. Dark blue means the TDH is in the pump’s Best Efficiency Range, where the pump will run best and longest. If the chart gives you a choice of more than one pump, check for the type that best fits your application from the list below, then check for the lowest wattage, to save on operating costs.

• For Low Head, Low Volume applications, use Magnetic Drive Pumps (MD Series)
• For Low Head, Very High Volume applications, use Axial Pumps (L-Series) with 3″ or larger tubing
• For Medium Head, Medium Volume, use Asynchronous Pumps (TT-Series)
• For High Head, High Volume Applications, use Direct Drive Pumps (A-Series)
• For Solids and Dirty Water applications, use Direct Drive Solids Handling Pumps (PAF and SH-Series)

# How Often Should You Clean Your FilterFalls?

Atlantic FilterFalls are  one of the best designed upflow biological filtration units on the market. The low maintenance FilterFalls works in two ways to remove wastes. It removes visible suspended solids mechanically by trapping them in the filter pads, clearing the water. One type of bacteria that grows right on the filter pads consumes that trapped organic ooze.
###### Why use FilterFalls
The primary function of the filter is to remove the toxic ammonia and nitrites excreted by fish, converting them to harmless nitrates. This function is performed by a nitrifying bacteria which  lives in the filter pads. Without them the fish and animals in the pond would actually poison themselves very quickly in their own wastes. These bateria require a constant flow of oxygenated water and cannot survive drying or washing in chlorinated water. They take a long time to grow and a longer time to grow back. They are essential to the health of the pond. The longer the filter is left undisturbed, the better it will do its job. The filter should not be cleaned more than a few times a year; once or twice a year is typical. Look for greatly reduced flow as an indicator of when to clean it, or wait till the end of the season before closing it up for the winter.
To keep the bacteria alive, take the top pad out and keep it in a bucket of pond water so the bacteria doesn’t die. It doesn’t need to be perfectly clean. Only wash the bottom filter pad in chlorinated water. Put the top pad down on the bottom and the cleaned pad on top and fill the filter with pond water. The check valve at the pump will keep the water from draining out of the filter. Reassemble the filter and start the pump. The water from below will help the undisturbed pad reseed the cleaned pad above it, ready for next year.
So relax, enjoy your pond and rest assured that your filter is doing its job without much intervention needed.

# Steps for Spring Cleaning your Pond

Well, it’s finally here, a month late in my neck of the woods, but worth waiting for. Time to get your pond up and running after a long, cold winter!

###### Step 1

The first step is to remove any pond netting installed in the fall. It may be heavy with leaves and debris that have accumulated over the winter. This is good news, because anything trapped in the net would have settled to the bottom of the pond. Clean and dry the net. Use zip ties to repair small tears before storing, you’ll need it next fall.

###### Step 2

The next step is to clean the filter media without killing all the beneficial bacteria living there. Those are the bacteria that convert toxic ammonia that your fish excrete continuously to harmless nitrates. They cannot survive drying, and your fish can’t live without them. Get a couple of suitably sized buckets and fill them with pond water. Rinse any bagged media in the pondwater and leave the media in the bucket, to prevent the biofilm from drying out. Then take the top filter pad out, rinse it in the other bucket of pond water, and leave it there. Don’t worry about getting it really clean; the bacteria is what counts and you’ve saved enough to reseed the filter.

###### Step 3

Now you can pull out the remaining filter mat(s) and clean out the FilterFalls with a hose or wet/dry vac. The closer to the bottom the mat is, the more gunky it will be, and will probably need more aggressive cleaning. Use the hose and rinse the other mat or mats really well. The chlorinated water will kill whatever bacteria remain but that’s ok. When you’re ready to reassemble the filter, the clean mats will go back on top of the mat you kept in pond water. When the pump turns on, the flow of water up through the biologically active mat will help recolonize the top pads.

###### Step 4

Now for the skimmer. Begin by removing the debris net, mat or brushes and clean them well. In the skimmer the bacteria don’t matter as much as ensuring that water reaches the pump. If your pump and check valve overwintered in the skimmer, remove and clean them now. If removed in the fall, clean and inspect your pump and check valve. Lock the weir door into the closed position and remove any debris in the bottom of the skimmer with a wet/dry vac. Reinstall the pump, check valve, net, mat and/or brushes. If you have an auto-fill installed inside the skimmer, test to make sure it is working properly and adjust the level if necessary.

Unlock the weir door and replace the skimmer lid.

###### Step 5

Remove as much debris as possible from the stream and pond before starting your pump. Remove algae and leaves from the streambed by hand. Use a net to fish out any algae growth and debris from the bottom of the pond.

Once you have cleaned out both the pond and streambed, take the wet mat from the bucket of pondwater and place it on the grate at the bottom of the FilterFalls, then place the clean mat(s) on top of it. If there is bagged media, set that in the filter, then cover with rocks and stones to camouflage the filter. Before the mat/media can dry out, turn on the pump.

As the water clears over the next week, remaining debris will become more visible in the bottom of the pond. Remove the visible debris and rinse out the skimmer mat and net.

ANNOTATION:

When everything is up and running, inspect the pond for any visible leaks. Keep an eye on the water level over the next week, so any problems that may develop can be dealt with early in the season.

After the pond has been opened and water temperatures have reached 50 degrees on a consistent basis, you can begin to use treatments.

Beneficial bacteria will help kick-start your eco-system and get your water clearer, faster. More frequent usage of Biomax+ for a couple of weeks after opening your pond, will help seed bacteria into the biological filters.

1. ReVive will dechlorinate the water if you have changed or added water in the spring.
2. If the pond is really cloudy, you can use QuickClear to drop suspended solids to the bottom of the pond and clear the water.
3. EcoKlean is a great oxidizing product to help remove debris from the stream bed and the bottom of the pond in the spring.

# How To Properly Conceal a Biofilter

So, there’s been a lot of good, sensible talk out there about how hard it is to hide a giant plastic biofilter at the top of the stream you’re building. In all fairness, when it’s just sitting there, exposed, before rocking around it, hiding a sizeable biofilter can seem near impossible. But there are simple, solid techniques to hide those big black boxes, and some compelling arguments in favor of using biofilters to start streams.

The advantages of having an upflow biofilter are well-known and pretty convincing. In general, they hold an impressive amount of filtration that not only removes suspended solids but provides surface area for beneficial bacteria that consume ammonia and nitrites. Their position at the top of an elevated stream usually means they can be plumbed with a drain valve, so they can be rinsed or backwashed easily. More complete cleaning may need to be done only once or twice a year, because of the way upflow biofilters work. The pump forces water up through the filter media under pressure, so the media tends not to clog easily; although the water may channel around the media, it won’t stop flowing. Finally, the ability to securely attach both the plumbing and the liner to the filter to start the initial waterfall has eliminated the most common leakage point in stream construction.

ATLANTIC’S BF1600 COMPLETELY HIDDEN BY ROCKS

### technique

SETTING THE FILTERFALLS INTO, RATHER THAN ON TOP OF THE ELEVATED AREA

Hiding a well-designed biofilter is primarily a matter of setting it into, rather than on top of, the elevated area. This is typically formed by mounding the excavated soil from the pond or reservoir. After the filter is properly set, then it’s a matter of simple rock placement. In nature, a stream cuts its way down in the surrounding land; waterfalls form as the flowing water scours out a pocket in softer soil or rock behind a hard surface. In theory, we want to bury the biofalls behind that ‘hard surface’, the rock or stone the water will flow over. What often happens instead? The biofalls is placed on the ground and soil is heaped around it up to the top of the box, then rocked, to form the utterly unnatural ‘water volcano’ we all love to hate.

BF2600 FILTERFALLS HIDDEN UNDER ROCKS

It’s a simple mistake, and just as simple to avoid. I prefer to mound and tamp the soil first, then carve out a space for the filter, then plumb to the front of the filter, but the box can be set and plumbed first – to each his own style. The point is, the soil has to end up higher than the top of the box, so the water flows out from about two-thirds up on the slope. If that requires digging the filter down, so be it. Then, I excavate the tamped soil away from the front of the filter, cutting a vertical wall the width of the filter to either side. I dig down until I reach the level of the bottom of the splash pool at the base of the falls. Then I attach the liner, leaving a couple of loose folds below the lip, to allow for settling and adjustment. Now I can start the stream by setting rock to create the first fall.

The idea is that building the waterfall is the objective, not hiding the filter. That will come by itself if I accomplish three tasks. First, I need two ‘shoulder’ rocks on either side that are taller than the filter, set to cover the ends of the spillway or opening of the filter. Next, I set a spill rock, or rocks, between the shoulder rocks up to the height of the spillway.

Now I need to fill between the rock and the filter to stabilize the falls. I usually have the space behind the shoulder rocks to push soil in behind the liner. If not, I’ll just fill any void on top of the liner with rounded stone. Either way, I’ll foam between the liner and the rocks, sealing the space so all the water goes over rather than around the spill rocks. As a finishing touch, I set small, flat rock on the ledges and grate inside the filter to finish hiding it.

Sounds simple, and it is. Working ‘backwards’ on the falls instead of focusing on hiding the filter actually hides it better. Couple of quick recommendations:

1. Get the largest filter you can fit. The larger the filter is, the easier to hide, because the stones set on the grate or ledge can be larger without compromising the flow or forcing water up over the sides. Of course, having more media and settling volume can only help as the pond matures and organic loads increase.
2. Tilt the filter forwards a couple of degrees, on a well-tamped base. Nothing worse than having a filter settle and water leak out over one side or the back.
3. I always plumb the filter with a cleaning drain, and use Matala semi-rigid mats, to allow for fast periodic backwashing. This reduces the frequency of tearing the filter apart for major cleanings to once every couple of years.

If you have any questions or tricks to concealing a biofilter please comment below.

# Tools That Don’t Suck – Tirolessa Sprayer

As water feature installers, my sons and I are used to hard, dirty, sometimes dangerous work. We enjoy what we do, whether it’s digging ponds, plumbing pumps, rolling boulders or tweaking waterfalls, but we also value anything that helps make the work easier or more fun. We’re always looking for tools, apps or gadgets that save time & effort, eliminate stress, add to our comfort on the job or are just fun to use. Often a buddy will turn us on to one. I’d like to return the favor by passing our favorite Tools That Don’t Suck along to you.

Tirolessa Sprayer

Every now and then a tool comes along that does a job simply and inexpensively, that otherwise would have required a major investment in time, energy and equipment. Typically, these tools are born of necessity, because someone, somewhere doesn’t have access to the technology – or the money – to get the job done any other way. Today’s entry in the TTDS category is that kind of tool.

I ran across the Tirolessa sprayer online a dozen years ago when I was investigating building a dome home. I had this idea about an ecotourism bed-and-breakfast in the mountains of Michoacan, Mexico, where the Monarch butterflies go on their amazing winter migration. I figured I could create really cool, inexpensive and energy-efficient housing modules by covering an inflatable mold with multiple thin layers of fiber-reinforced concrete, building up the layers successively until the structure was strong enough to resist not only weather, but earthquakes too. The trick is to get a thin, strong first layer of concrete without deforming or collapsing the plastic balloon form. After the layers are self-supporting, the form is deflated and the rest of the concrete dome built up by troweling. The Tirolessa sprayer was recommended as the ideal tool to apply those first thin layers.

Well, just about the same time as I was pipe dreaming, I was asked to build caves and huge artificial boulders around a 200-foot-wide pond cover an interior wall with waterfalls. I had just finished plumbing and tweaking a Hawaiian-themed “black lava” waterfall in a restaurant. A Gunite crew had been called in to form the structure out of rebar covered with wire lathe and shot the whole wall with very wet black cement. I bought the Tirolessa thinking it might replace the Gunite crew – and it did. I wasn’t very good at texturing the final product, but there was no doubt about it. This little gadget could really blow some mud.

Yes, blow. The Tirolessa is basically a stainless steel bucket with air holes at the bottom. The handle is a hollow steel tube to which an airhose is attached, with a trigger. Pull the trigger and air blows inside the bucket across the bottom and out the front-facing air holes, carrying a spray of very loose concrete slurry with it. We make a mix of two parts fine sand to one part Portland cement, with enough water to give it a consistency between pea soup and oatmeal. Scoop a bucket of slurry from the wheelbarrow, hold the bucket two feet from the vertical surface to be covered, pull the trigger and spray the slurry. And repeat.

We’ve found the Tirolessa invaluable for getting that first critical layer on difficult vertical surfaces, and that has opened a whole new range of possibilities for us. Now we can easily protect the inside of any EPDM pond without building inner walls. The Tirolessa still can’t make concrete stick to rubber, but it CAN make cement stick to vertical geotextile, no problem at all. We cover our vertical liner walls with a layer of geotextile, well-anchored at the top so it will support the weight of the cement we spray on it until the first layer dries. If needed, we spray another layer on that until the curtain of concrete-covered fabric is stiff enough, then we switch to troweling on additional layers, this time with chopped polypropylene fibers mixed in.

By the time we have 4 to 5 thin layers, around an inch and a half thick, the skin will withstand a blow from a sledge hammer. We often add powdered black dye to the last coat so the finished pond appears bottomless; it also enhances the colors of koi. And it all starts with one of my favorite Tools That Don’t Suck, the Tirolessa sprayer.

# Are You Connected to Your Water Feature?

Are you connected to your water feature? Sounds like an odd question? You might think I’m heading in the direction of getting you re-connected to nature. You know what I mean, how in today’s world we have a shortage of nature in our daily lives and having a water feature is a great way to remedy that problem. If you have children, your water feature can be their connection to nature as an outdoor classroom to study the eco-system without them even knowing it. All of that would make a good article however that’s not the direction I was heading.

Instead, I was just curious if your current water feature has a Wi-Fi connection? Now I bet I have your attention, you didn’t think your water feature needed a Wi-Fi connection did you?  Well in today’s world who would expect anything else?

With the addition of two new Atlantic Water Garden products your water feature can join the high tech world. Atlantic’s Triton Ionizer and pump variable speed control both have their own Wi-Fi connection making your life that much easier and your water feature more interactive.

The Triton Ionizer ionizer is designed to mineralize the water helping keep water features clean and clear without the use of harsh chemicals and is safe for fish.  The unit can be controlled manually from the front panel or by the use of the ionizer mobile Application for iPhone or Android devices.

The TidalWave VSC allows you to vary the output of Tidal Wave TT & TW-Series Asynchronous pumps wirelessly by remote control or mobile app! The VSC allows you to set both on and off times as well as drop to 25% of the total flow in 10 levels of adjustment giving you the ultimate control over water flow.

Both of these products make life with a water feature more enjoyable. Previously the downfall has always been the effort to disguise them into the landscape during installation usually ending up in a location that is tough to access. With the new connect ability, you can hang out on the patio and play with your pond from your lounge chair. You see some debris in the waterfall, open the ionizer app and increase the level. Or the reverse can be true, you don’t see any debris in the water feature, open the app and lower the level of activity.

The variable speed control is even a little more interactive, as your mood changes so can the desired flow of your waterfall. If you are having a party and want the waterfall to really put on a show, open the VSC app and turn up the volume or it could be a quiet afternoon on the patio, open the app and lower the volume a little. The VSC can also be programmed to control your feature with its on/off programmable timer. This is a nice little feature that helps you to save electricity and water by having it turn off when you are not around to enjoy it.

So sit back in that lounge chair and visit www.atlanticwatergardens.com and learn how you can get better connected to your water feature!

SEAN BELL

Sean is the Regional Sales Manager for the Southeast for Atlantic Water Gardens. Fish Geek and water feature enthusiast, Sean has managed one of the largest aquarium stores in the Southeast while running his own pond maintenance company. When it comes to water features, Sean is your guy!

# What Happens to My Fish in the Winter?

Probably the number one question a prospective pond owner will ask is “what happens to to my fish in the winter? The quick answer is “not much”, but there is a little more to it than that. Truth is they really just slow down, some will say they hibernate, others will say that they go dormant, but it is more of a torpid state. Their body temperature is regulated by their surroundings, so as temperatures drop, so does their activity. On the coldest of days you will see them sitting on the bottom of the pond with their fins tucked in. If they could talk they would simply say they are waiting on spring.

“Should I do anything for my fish?”,absolutely, but it’s probably not what you are thinking. Your fish are tough and can handle the elements on their own very well. But they do need you to help out in a minimal way.

First thing is to feed them a good quality high fiber fall/spring fish food. Your fish do not handle food the way we do. They continually graze and eat to fill the pipeline. When temperatures drop, that food is stuck there to decay and cause issues in your fish. They can not empty their digestive tract after temperatures have dropped. Feeding should be stopped when water temperatures reach 55 degrees. Keep an eye on the weather, quit feeding at the 60 degree mark to be safe. If you live areas of the country that get big swings in temperature as fall approches, use your best judgement erroring on the side of caution.

Next thing to consider is your fish really need is consistency. They can handle the lower temps but they really need it to be consistent. Make sure your pond is at the very least 2 feet deep. This will give them a safe zone to be in for the winter. The warmest water is the deepest and should not be disturbed. If you have a waterfall make sure that where it enters the pond is somewhat shallow. If the waterfall drops into the deepest section of the pond it will “mix” cooler water into the “safe” zone your fish are living in. Leaving your waterfall running in winter is fine to do as long as that cooler water is being pulled from the surface zone (using a pond skimmer) and being returned to the surface zone. Big temperature swings in your pond will stress your fish and lead to health issues.

Lastly, is to make sure there is an open hole in the surface of the pond. If you live in the colder climates, your ponds surface may freeze over completely. Even though our finned friends are not breathing as much as they normally do, they are still breathing. If the surface is completely covered in ice, harmful gasses can not escape and the pond can not re oxygenate as it normally does. Use a small pump or and air system to keep a hole open in the ice. Place the small pump on the upper shelf of the pond pointed to the surface. It should “bubble” above the surface. If you elect to use an air system (preferred), Place the air stones on the upper shelf of the pond. Both ways will help in keeping a hole in the ice. But do not put either the airstone or pump down in the safe zone. That would mix the warm water your fish are enjoying with the rest of the pond, thus leading to health issues.

If you follow these simple ideas this winter your fish will do great and be ready for spring. As mentioned before, no feeding at 55 degrees and below. As spring starts to show, be sure temperatures are consistent before you start feeding again.

SEAN BELL

Sean is the Regional Sales Manager for the Southeast for Atlantic Water Gardens. Fish Geek and water feature enthusiast, Sean has managed one of the largest aquarium stores in the Southeast while running his own pond maintenance company. When it comes to water features, Sean is your guy!

# The CICY Project – From Orchids to Cenotes

It all started at the IWGS Symposium, in an orchidarium in a salt mine one hundred feet below Kansas City. I was chatting with a lovely couple, Porfi and Beatriz, long time members of the International Waterlily and Water Garden Society, IWGS or I-Dub for short. We chatted as we ogled the 10,000 or so magnificent orchids at Bird’s Botanicals that flourished in the controlled temperature and humidity of the vast underground caverns. (If orchids in salt mines sound pretty cool to you, consider joining – the IWGS and its members are very interesting indeed.)

The subject was the artificial ponds and lakes of the Yucatán Peninsula. I’ve been traveling to Mexico for number of years, trying to help our distributors in Yucatán maintain the many large water features that are built using swimming pool technology. Unfortunately, lakes are not large swimming pools, as my friends Lydia and Nacho Barroso can attest.

As the owners of a very successful pool and spa distributorship that has expanded into every facet of water technology, the Barrosos have found through years of experience that chlorine and sand filters cannot adequately deal with the sun and heat of southeastern Mexico. The large shallow artificial lakes at every golf course, country club, condo complex and resort on the Peninsula require a different strategy. Years of trial and error have proven phytofiltration, cleaning and clearing water with plants, the best course of action. While we strolled through the cavern, I asked Porfi, who lives near the Barrosos, if he could help, and he knew just where to find aquatic plants.

Then he asked if we knew about a pond project coming up at a local botanical garden. That’s how we found out about the Centro de Investigación Científica de Yucatán, or CICY (pronounced SEE-see). I Googled it as soon as we got back from the tour. According to the webpage, CICY is “a public research institution (whose) mission is to generate scientific and technological knowledge in the areas of plant biochemistry and molecular biology, agricultural biotechnology, natural resources, materials science, water sciences, and renewable energy in order to contribute to sustainable development.” What could we do for el CICY, I wondered?

My next trip down to Merida my friends and I stopped by for a look around. They have some really cool stuff there, including a cloning lab and a huge collection of native plants, and they were about to put in a new Sensory Garden. Porfi knew the architect and the botanist in charge of the gardens, and had heard that the centerpiece of the new Sensory Garden was to be a pond – would we be interested building it?

Would we ever! This was a golden opportunity to show off just what active bog filtration could do, in a public garden that would receive 150,000 visitors a year. Now to make it happen…To Be Continued.

Read “The CICY Project – Part 2”

DEMI FORTUNA

Demi has been in water garden construction since 1986. As Atlantic’s Director of Product Information, if he’s not building water features, he’s writing or talking about them. If you have a design or construction question, he’s the one to ask.

Illuminating your outdoor space can be tricky. How many lights do you need? Where do you place them to get the best lighting during the evening? Where and what are the best aspects to highlight in a water feature?

In a pond or waterfall you need to be very careful with the placement of light. Even in the water, light can be blinding to someone who is looking into your pond. A good rule to follow is always place the light facing away from the viewing area.

In this picture the lights highlight aspects of the pond but are facing away from the main viewing area. These lights are small enough to be placed in the water and to be hidden within the rocks around the edge of the pond.

The amount of lights you use is completely up to you depending on how bright you want your water feature to be at night. If you have a lot of focal points that you want to highlight, use as many lights as needed to illuminate the area. You should want to focus on the main aspects of the water feature that draw the most interest.

For example, you would not want to place a light into a stream that is flat with not a lot of water movement. By placing the light on the falls of stream beds and waterfalls, you create a more visually interesting feature at night.

The shadows cast on buildings from the movement of water and light will create a very dynamic effect that will make a lasting impression.

Another tip for light placement is to stagger the lights throughout the landscape or area to create balance. The goal is to move the viewers eye through the entire space, using too much light in the foreground will prevent viewers from experiencing the entire water feature.

Do you have  any other tips or questions on light placement? Post them below.

JIM CHUBB

Jim has 26+ years of sales experience and 16+ years in the water garden industry

# Bog Filtration, the perfect complement to Biological Filters

Last month my buddy Jim Chubb talked about the importance of biological filtration, why you’d want to use a biological filtration box, and how to hide a FilterFalls. In this post I’m going to talk about a complementary approach to biological filtration, the Bog Filter.

Bog filters are the perfect companion to biological filters, because they help complete the nitrogen cycle that begins with biofilters like the FilterFalls Jim was talking about. Biological filters harbor the bacteria that convert ammonia from fish wastes into nitrates. Bog filters take those nitrates out of the water column and convert them into plant material.

The reason this is so important is, the nitrates that result from a well-functioning biofilter are plant food, and if there are no other plants in the system, or even too few plants, those nitrates are going to feed lots and lots of algae.

That’s right. The better your biological filtration is, the more plant food is going to be created, and the more algae will grow… UNLESS there are other plants to consume those nitrates.

Enter the Bog Filter, the perfect way to get those nitrates out of the pond water, and so, to eliminate green water and string algae. Basically, by placing desired ornamental plants in bare gravel, without sufficient soil to feed themselves, the plants take up all the available nutrients in the water and starve out the undesirable algae.

Bog Filtration is a pretty simple concept, so there are plenty of different ways to implement it. The simplest are graveled areas in or adjacent to the pond filled with bog and marginal plantings, called passive bogs because there is no active flow of water through the gravel. Active bogs use the pumping system to force water through the planted beds, and are much more effective because all the nutrients in the pond have to pass through the matted roots of the bog filter, and are removed.

There are two kinds of active bogs that differ in the direction of water flow. Downflow Bogs pull water down into the planted gravel bed, while upflow Bogs reverse the flow, pushing water up through the plant roots and out the top of the gravel bed. Because downflow bogs tend to trap sediments and clog more frequently, we’re going to talk about building upflow bogs instead.

The advantage to active upflow bogs is that they can be placed just about anywhere. Perimeter bogs, waterfall or stream bogs, even bog islands are simple to add to any existing pond, as long as they are built so the pumped water makes its way back into the pond.

One of the most effective bogs I’ve seen was built on an island in the center of an existing koi pond. A plastic grate set on cinder blocks about 6” below water level was covered with a piece of liner, then ringed with dry stacked stones to the surface. A planted gravel bed covered a 2” perforated pipe attached to a pump below the island. Water pumped into the gravel bed flowed back through the gravel and stones, stripped of all nutrients.

It doesn’t take much flow – usually one quarter of the volume of the pond per hour is sufficient. The size of the bog depends on the fish load. A goldfish pond where the fish are not fed at all might need a bog about 10% of the surface are of the pond in size. On the other hand, a pond where Koi are fed twice a day might need a bog 30% of the size of the pond.

More elaborate bogs use EcoBlox under the gravel bed to form a sediment chamber that also traps suspended solids, but that’s the subject of another post. Regardless of how you choose to install them, Bog Filters keep your pond free of algae using just beautiful plants to clear and clean pond water.