It has been said that necessity is the mother of invention. Perhaps she is also the mother of adaptation and innovation. Here is the story of how I have applied my meagre knowledge of the aquaponic and hydroponic concepts and developed a system to provide fresh water and greens for my ducks.

An important point to make about quackuaponics, as devised by me, is that the primary reason for using the system differs from the primary reason behind hydro and aquaponics. The first goal of quackuaponics is to provide a rough bio-filter, which discharges fresh, clean water for the ducks to use. (I am using the terms fresh and clean very loosely). Of course there is the usual symbiosis; the growing of plants using nutrients trapped by the filter, along with those in solution passing through the system in the water. The growbed however, is primarily a filter.

Origins of quackuaponics

Not long ago I watched a news article about a duck farm that had been raided by animal welfare activists who videoed the poor state of the ducks. Hundreds of them in each shed languished in filth. Water to drink was provided by chicken farm style drippers. No water at all was provided for the ducks to use to wash, preen and breed in. The situation was appalling.

The farmer explained that whatever water the ducks were given, they fouled and ruined immediately. There was no way the farm could provide regular fresh water to these large flocks and stay in business. I understood completely. I keep ducks. They provide eggs; they help control insect pests and provide fertiliser for the lawn and garden beds. They are also animated lawn ornaments and quite entertaining to watch.

My ducks like to have lots of fresh water, which they quickly turn foul and muddy. This filthy water they go on liking just as much, if not more so. Given that ducks will do far better with regular provision of fresh water, I go out of my way to empty and recharge their pond and other containers about the place almost daily. It is hard work, and my devotion to the ducks shows for all to see on my water bill. I had a rainwater tank installed and this helped, however I quickly found that my 1,320-gal. tank needed to be doubled to limit using water from the city system. Slowly, my quackuaponics system began to evolve and throughout its gradual development, scalability has fortunately remained.

Duck behavior

One really notable difference between quackuaponics and aquaponics would have to be hygiene. Whereas aquaponics must be clean and controlled for the sake of avoiding illness and disease for both plants and fish, quackuaponics is a filthy game. Aside from their excretions, ducks have some other dirty little habits.

Here is the typical scenario: if a large tub of fresh water was placed among some ducks, with a hose running into it, allowing it to overflow at a nominal rate, the majority of the little flock would partake in the overflowing water on the ground, using it to muddle into the surrounding soil. They would grovel away with their bills and create a muddy little wetland.

They consume water, sand, dirt and plant matter, and whatever else they can stir up with their bills. They use a washing process inside their bill, crop and gut to separate foodstuffs from soil and sand in a fairly haphazard way. As the sordid banquet continues, the ducks will move in and out of the tub, continuing the digestive process all the while. By way of their frolicking, splashing, washing and mating ducks cause loads of overflow.

In just hours, a heavy sludge will develop in the bottom of the tub. Ducks will mill through this sediment with their heads underwater, stirring it and seeking scraps of nutrition from it. This is the mode of eating the duck prefers. When I give them comfrey, lettuce, grains, layer-mash and scraps, or when a duck snatches a large grasshopper, the duck will take it to the water and make a stew from it, pulverising it with its bill, drinking and filtering the result.

Indeed, emptying and refreshing the tub after one day is a dirty and smelly job. Emptying and refreshing the tub after three or four days is a putrid, disgusting smelly job. Ducks are not called fowl for nothing! Oddly enough, given a reasonable water supply, the ducks manage to do all this and remain squeaky clean.

Note that it is quite important to maintain proper personal hygiene while working with the quackuaponics concept. You are going to come in contact with the filth. You must wash your hands. If you uproot a nice big lettuce and shake it around to free up the grow-media gravel from the root ball, it’s going to splash back into your face.

Since I’ve been developing and running my system, I’ve always been in contact with the filthy aspects of the system and I’ve not yet suffered any real illness worth recalling even after regularly consuming plants and eggs from the system.

To bring it back to the first goal of quackuaponics, though, it’s about taking out all these solids, dirt and sands, partially digested and undigested foods from the water, and returning the water for re-use in a reasonably clear and odor-free state. The following is an overview of my basic system.

Components you'll need to start a quackuaponics system

Reservoir

Essentially the duck pond, this is an acrylic tub about 50-gal. Ducks mess around in here, injecting nutrients and other solids to the system.Typically the bottom is covered with a drift of fine sand—the product of the filter feeding process. The lighter solids are taken up by the system and eventually end up in the growbed and filter.

I occasionally scoop the majority of this sand out and dispose of it on nearby garden beds. If I am nearby and realize the pond is about to be pumped out, I can give the water a good stir with a broom, ensuring settled matter is taken up by the pump and enters the rest of the system. In most cases though, the ducks and the discharge flow can do enough agitating for the system to work without me.

Dirty water sump pump

This pump is a heavy duty dirty water pump and its run times are one or two minutes per hour. It virtually empties the pond in that short time, which is not long enough to see the pump really run dry. Its specifications tell me it can take solids up to 1.37 in., and as such I expect it will take whatever matter the ducks drag into the pond, along with the odd discarded feather. It sits on the floor of the pond and it’s common to see a duck or drake ride the water level down and then take advantage of the low tide to forage through whatever sands and debris cover the pond floor.

Settling tank

The secondary reservoir is a large plastic barrel standing on end. It has a drain cock, which I have not so far used. This barrel allows for some settling, and there is a decent amount of sludge sitting on the bottom. It was added to the system for another very important reason: in summer, the water in the system ran much too hot. My big shallow growbed acted like a solar panel, and water discharging from the bed sometimes exceeded 86°F. By adding the settling tank, and more than tripling the system’s water capacity, temperature instantly dropped and has since remained below 66°F.

The settling tank is also where an automated top-up line enters the system. A big difference in comparison to a standard hydroponics system is that dilution by rain and by topping up is not an issue. My growbed is populated with compost worms, and they are working alongside the nitrobacteria, struggling to keep up with the digestible matter trapped in the bed. I have a top-up line fed into the settling tank on a timer via a float valve.

This gives the system a shot of water if needed and serves another important role: allowing me to leave the system alone for days. There is a tee junction in the top-up line feeding a misting hose. This misting hose, which runs across various garden beds, is also suspended about 4 ft. above and run the length of the growbed.

Without the misting hose, the top-up line occasionally over-pressurizes and bursts free once the float valve had shut off flow. Now, the misting line runs on gentle idle until the settling tank level causes the float valve to shut off. Then the misting hose runs full force for the remainder of the time period—only five minutes total. In the event of otherwise catastrophic pump timer failures in the main system, this daily five-minute misting can keep all the plants alive until I return and set things right. In hotter months I boost this aspect of the system to two five-minute runs, one in the morning, one in the evening.

Outflow pump

This is just a little pond fountain pump. It is mounted about halfway down in the settling tank. Settling tank levels vary from just over half full to almost full when the system is running properly. The outflow pump is timed to run a few minutes after the main reservoir pump has stopped, and it is set to run for four minutes, as its flow rate is around half that of the dirty water pump. This outflow pump sends water to the top of the growbed where a buffer tank helps moderate flow.

Buffer tank and flow control manifold

This is a largish plastic tub resting on the intake end of the growbed. Even though the outflow pump is the smallest in the system, the growbed may flow too slow, restricted by root proliferation and trapped solids building up, and will overflow at the top end if fed directly with enough water.

The buffer tank has a rudimentary drip manifold running from it, made of drilled 0.78-in. electrical conduit. This manifold runs three quarters of the way along the growbed. It comes from a loose-fitting a hole in the side of the buffer tank, and inside the buffer tank it bends to one side at a 90-degree angle, extending inside the buffer tank. By adjusting the elbow to be tighter or looser against the hole in the buffer tank, and by turning the conduit so that the open end inside the buffer tank is at a deeper or shallower in the buffer tank, outflow can be infinitely adjusted.

If the elbow is loose against the hole, more water passes around the conduit and directly into the top end of the growbed. However, when the top end of the growbed is tending to overflow, I simply pull the elbow of the manifold tube more snugly into the orifice, so more water must then flow down through the manifold, dispersing neatly across the length of the growbed, avoiding overflow at the top end. To simplify, the buffer tank allows much more water to be sent to the top of the growbed during a shorter pump run.

Growbed

The growbed is a tray 2-ft. wide, 16-ft. long and only 4-in. deep. The tray is lined with plastic, and the grow media is small sharp gravel. As the primary purpose of the system is filtration, there is no place for an auto-siphon of any sort. The water and nutrients should pass (if possible) the full length of the growbed, which could be more correctly referred to as the filtration bed.

I see the depth of the growbed as a short-coming in the system. Growbed depth should ideally be closer to 12 in. The compromise exists because of the materials at hand when building the system and the lighter weight suits the supporting structure. The bed runs at a slight slope to save the plants from the ducks, and save my back as I tend to the plants.

The growbed discharges into a small section of roofing gutter, which has a down-pipe, sending the discharge as a little waterfall, back to the pond (the primary reservoir). This waterfall assists with aeration, agitation and cooling, and seems very enjoyable for the ducks during their use of the pond.

Plants

I’ve populated the growbed with a wide variety of plants, such as various forms of basil like Greek, Thai, lemon and standard basil. There are always several types of lettuce through the bed, and most of these end up self-seeding to some extent. These are shared between ducks and humans. I have had great success growing burpless cucumbers too. Capsicums and chillies grow and fruit well. Strawberry plants are certainly growing well, though they have not so far produced worthwhile fruit. Rockmelon vines grew well, also poorly fruiting.

Other pants inhabiting the bed are cauliflower, thriving clumps of garlic, chives and rosemary. I consider a plant to be pulling its weight in the system as long as a decent root system develops. In other words, the plant must play a part in the filtration process. If things are also going well above ground, that’s a bonus.

One plant I have found to be unsuitable is tomatoes. These did a little too well, and the massive matted root systems gagged the growbed, restricting flow almost completely, causing the bed to overflow excessively. On the subject of roots, I seem to be able to leave any broken-off root matter in the growbed without problem. This left-over root matter rots down quickly and adds to the nutrient mix.

Additives

When I first built the system and began to cycle I researched aquaponics to kick the growbed into action. I wasn’t really confident the system would work at first. The plants weren’t doing too well, probably because the nitrobacteria hadn’t yet populated, so I began to collect an array of hydro-style chemicals and research mixing rates and ways to add them to my system.

Thankfully, the system began to work, but I was left with several compounds and elements that I didn’t really need. After a while, I learned that some of them could still be useful and not harmful. I now add chellated iron, sulphate of potash, and Epsom salts all dissolved in hot water about every month to six weeks. I have recently tried adding a little of the sulphate of potash to the buffer tank.

It is heavy and sits on the bottom dissolving slowly. I also add seaweed-based liquid fertilizer. The aim is to shore up deficiencies in the plant’s nutrient base. It’s a difficult game but now that the growbed has matured I’m certain the system will run happily without additives.

Other adjustments

The system is fairly stable, but there are behavioural variations I need to manage, which mainly effect flow. Levels of solids and nutrients can vary wildly with the behaviour of the flock as the seasons change. Differing foods are available, distractions such as mating, egg-laying and brooding arise, and flock size can vary for many reasons.

The flow of solids can vary to some extent without need for adjustment. If things get too heavy though, there is a chance the growbed will overflow. A strategically placed bucket catches some of this loss, and the ducks don’t mind puddling round in what ends up on the ground. My top-up system takes care of water loss and I can decide on making adjustments to the buffer tank manifold when I see overflow appearing in the overflow bucket.

Final thoughts

Though happy with my system, I’m always considering modifications and alterations. Many concepts and ideas and experiments have led to how the unit runs today, and no doubt new concepts, ideas and experiments are ahead.

I’m pleased to say that the unit can be scaled up to an industrial size, and whatever I do to it, I will seek to maintain scalability. For the future I envision a duck farm complete with a sizeable collection of hot-houses producing a marketable side product of lettuce or cucumbers, as well as providing some feed and better