Backyard Aquaponics Made Easy

by

Andrew Handley

Table of Contents

Introduction

Chapter 1: What is Aquaponics?

Creating a Cycle

Chapter 2: The Nitrogen Cycle

The Three Toxins

Toxin #1: Ammonia

Toxin #2: Nitrite

Toxin #3: NitrAte

Setting Up the Nitrogen Cycle in Your Aquaponics System

Speeding Up the Process

Prime Temperature Conditions

Prime pH Conditions

Regulating pH, Ammonia, Nitrite, and NitrAte

Chapter 3: Types of Aquaponics Systems

The Raft System

The Continuous Flow System

The Ebb and Flow System (Flood and Drain)

The CHIFT PIST System

Chapter 4: The Bell Siphon Valve

Chapter 5: Types of Fish

Stocking Density

Chapter 6: Types of Plants

Chapter 7: Starting from Seed

Seedlings

Seeds in Coir

Sowing Seeds Directly

Staggered Growth Method

Aquaponic Growth Rates

Chapter 8: Types of Grow Medium

Grow Media MUSTS

Most Popular Types of Grow Bed Medium

Chapter 9: Homemade Fish Food

Chapter 10: Vermicomposting

Conclusion

Introduction

Food shortages across the globe. Agricultural runoff. Drought. Decreasing land mass for commercial food production.

These are problems that have become more and more prevalent in recent years as populations increase and the available resources for traditional means of agricultural dwindle away at an alarming rate. The problem isn't the technology, however; it's the way we're using that technology.

Aquaponics can change all of that, and believe it or not you don't need a Ph.D to understand the complex biological processes involved in the natural micro ecosystems that occur when you combine two different but complimentary life forms.

Animals create waste. Plants use that waste for their own benefit, cleaning it out of the environment. The cycle continues. The circle of life.

You see it in the air around you: We breathe in oxygen, exhale carbon dioxide. Plants use the carbon dioxide for photosynthesis and produce more oxygen. The cycle continues. The circle of life.

You see it in the ground beneath your feet: Animals and plants die. Bacteria break down the organic matter into proteins and minerals, which allow fruits and vegetables to grow

and provide food for the animals. The cycle continues. The circle of life. So it goes.

Why then should it be such a strange concept to take these natural cycles as the basis for our commercial agriculture? Nature already figured it out: You don't need tonnes of agricultural waste to grow a field of lettuce. You don't need gallons of chemical fertilizer and growth hormones to extract the full potential of a crop.

Natural. Self-sustaining. Limited impact, yet with enough production volume to feed entire populations.

These should be the catch phrases of our generation and the generations to come. These should be our goals for the future.

This book isn't about commercial-scale aquaponics. It's made for the beginners, the hobbyists, and the self-starters. This book is about the concepts and ideas that create this incredible thing known as aquaponics, giving everybody with an interest the tools and resources they need to start their very own aquaponics system. Once you have a firm understanding of these concepts, then scaling up to the commercial level, if that is your goal, is as simple as 3 grade multiplication.

There have been better books written about aquaponics in the past, and I encourage you to check them out. I'll provide links and names for these books at the end of this one. But if you're just getting into aquaponics for the first time and want something easy to read and understand, this is the right place to start.

Feed yourself. Feed your family. Feed your community. Feed the world.

Chapter 1

What is Aquaponics?

Aquaponics is a combination of two words: Aquaculture and Hydroponics.

Aquaculture: The culture of aquatic life forms. Anybody with a fish tank has participated in aquaculture. It's just a fancy name for growing fish. (Although crawfish, snails, shrimp, etc. also count).

Hydroponics: Soilless plant culture. In hydroponics, plants are grown with their roots in an inert grow medium rather than soil. The inert grow medium provides no nutrients on its own, so the plants' nutrients need to be provided via the water. Hydroponics on its own is an excellent means of growing food crops, but it comes with its own specific problem.

Creating a Cycle

Aquaculture and hydroponics on their own are excellent systems, but they lack the ability to sustain themselves. Fish create waste by breathing and eating, waste that needs to be cleaned from the water; plants require nutrients that must be provided from an outside source.

By combining the two systems, it's possible to eliminate both of those problems. The circle of life. Plant life pulls the waste products out of the water, in the process cleaning the water so that the fish can enjoy a healthy living environment.

Simple enough, but what are the real benefits to aquaponics?

        Aquaponics doesn't require the addition of any chemicals whatsoever. On the plant side, it requires less than one tenth of the amount of water typically used in hydroponic grow systems. On the fish side, the water requirement is less than one percent of what a typical aquaculture system would run through.

        Aquaponics allows for two completely separate food crops to be grown in the same space, further decreasing the amount of land required for sustainable agriculture. Tilapia, perch, and other commercially grown fish species thrive in an aquaponics system. Plant species are only limited by your imagination (more on that in Chapter 8).

        Despite all these incredible benefits though, there's one fact that makes aquaponics stand out as the most attractive choice for home growing: Anybody can do it. You don't need a background in horticulture or a degree in marine biology. You don't need to have any experience whatsoever to get started with aquaponics today and enjoy your first harvest in as little as a month.

One more note about aquaponics before moving on: It's affordable! There are some pre-fabricated systems out there that are selling for a thousand dollars or more. You don't need those.

If you're reading this, you may have already purchased my backyard aquaponics system for just over $100. If you bought this book from somewhere else, you can take a look at that system here: AquaFlow Ebb and Flow Mini Aquaponics System. A mere $100 investment is literally all you need to set up your own home system.

But I'll be honest, if you're willing to get creative, you can go out and purchase everything you need for less than that.

In fact, I would encourage you NOT to buy that system, and instead try to work out the pieces for yourself. It takes more time, and yes, maybe a little more money in trial and error, but you'll get a much more thorough understanding of how this miniature ecosystem lives and grows when you do it completely by yourself. Everything you need is in this book.

Outside of the initial cost, there are only two outside elements/expenses that must be added to keep an aquaponics system running:

        Fish food

        Electricity for a low watt water pump.

Both of these, however, can also be eliminated. With a simple 12v solar panel and a DC pump you'll never have to spend another cent on electricity. We'll cover the fish food problem later in the book. For now, let's get into the details of how this delicate ecosystem maintains itself with virtually no outside assistance.

Chapter 2

The Nitrogen Cycle

The entire setup and operation of an aquaponics system, all of those benefits mentioned in Chapter 1, depends on one thing running smoothly: The nitrogen cycle.

We took a simple look at it earlier:

A)    Fish create waste

B)    Plants filter the waste from the water and use it for growth

C)    Clean water goes back to the fish

The cycle continues. The circle of life. A B C.

The reality, though, is that for this to work there has to be a third organism living in the system, known as nitrifying bacteria.

These invisible angels are the backbone of aquaponics, converting the fish waste toxins into something the plants can actually use. There are three toxins that the nitrogen cycle has to run through.

Toxin #1: Ammonia

In their natural biological cycle, fish excrete ammonia as a waste toxin. In the wild, out in ponds and lakes and rivers, ammonia isn't very dangerous because it's diluted by all the water. In a home system, ammonia can quickly build up to toxic levels which become increasingly harmful to the fish, especially damaging their kidneys and gills. This leads to impaired growth and eventually death.

Normally, a fish farmer would need to replace the ammonia filled water with fresh water periodically to keep the ammonia concentrations down, but a naturally occurring bacteria does it for us instead.

Nitrosomonas sp. is a bacteria that consumes ammonia and produces nitrite.

Toxin #2: Nitrite

Nitrite is better than ammonia, but it's still toxic in large enough quantities. It reduces the fish's ability to absorb oxygen through their gills, essentially causing them to suffocate after enough time. Unfortunately, plants can't use nitrite either, so we need a second bacteria to convert it into something else.

Nitrobacter sp. is a bacteria that converts nitrite into nitrAte. (I'll be using a capital "A" for nitrate to make it easier to differentiate from nitrite).

Toxin #3: NitrAte

NitrAte is still toxic to fish, though not quite as toxic as ammonia or nitrite. However, it just so happens to be a perfect food for plants. So here we have the end to our nitrogen cycle. The nitrAte filled water is pumped into the plant grow beds, where the roots pull the nitrAte from the water, acting as a biofilter. The clean, chemical free water runs out the bottom of the plant beds and back into the fish tank. The cycle continues. The circle of life.

diagram source: http://aquaponics.totallytuft.com/HowItWorks/HowItWorks.htm

Setting Up the Nitrogen Cycle in Your Aquaponics System

This cycle doesn't happen overnight, not at first. In a new system, the nitrifying bacteria need time to establish. They will begin to grow on their own, but the process can take several weeks at the beginning. Here's a breakdown of the average time it takes for each bacteria to establish itself.

1.       For the first week, ammonia will build up and start to peak around day 7 or 8. During this time it's advisable to do a partial water change in the fish tank every 2 days. Remove about 20% of the water and replace it with clean, dechlorinated water to avoid reaching dangerous ammonia concentrations.

2.      After a week, the Nitrosomonas sp. (ammonia > nitrite) will begin to grow. These require approximately 2 weeks to reach the point where they can cycle ammonia as fast as it is produced.

3.      Three weeks into the system you'll begin to see the effects of Nitrobacter sp. (nitrite > nitrAte) taking hold. After about 1 or 2 weeks they will be established to the point where nitrAte is the only chemical present in the water. Using an aquarium test kit, the ammonia and nitrite levels should be at zero while the nitrAte continues to build. At this point the nitrogen cycle as been established.

Speeding Up the Process

If you want to speed up the cycle, you can add aquarium rocks or grow medium that has already been inoculated with both species of nitrifying bacteria. I include a bag of pea gravel established with bacteria in my AquaFlow aquaponics kit, but if you know a friend with an aquarium you can get it from there as well. This will typically cut the wait period in half.

Here are a few quick facts about nitrifying bacteria to help give you a mental picture of what you're working with:

        They require a surface for best growth. With nothing better to grow on they will form a film on the surface of the water, but they'll grow much faster with something such as gravel.

        Given prime conditions, Nitrosomonas sp. populations will double roughly every 7 hours, and Nitrobacter sp. populations will double roughly every 13 hours. In the world of bacteria, this is very slow.

Prime Temperature Conditions

        Nitrifying bacteria grow best in temperatures between 77º and 86º F

        If the temperature drops below 64º F, growth will decrease by 50%

        If it drops below 50º F, growth will decrease by 75%

        Below 32º F and above 120º F, the bacteria will die

As you can see, there's actually a pretty wide margin of error as far as temperatures are concerned, but when kept within the prime temperature range (77º - 86º F) they will grow fairly fast.

Prime pH Conditions

Nitrifying bacteria like a neutral to slightly basic environment. Nitrosomonas sp. prefers a pH range of 7.8-8.0, and Nitrobacter sp. prefers a pH range of 7.3-7.5.

Always aim for a high pH because the bacteria are more tolerant to basic conditions. Once pH drops below 7.0, production will start to go down, and at 6.0 they won't convert anything, giving you a sudden spike in ammonia.

A quick note here.

That lower pH number, the 6.0, was determined in a lab setting under sterile conditions. Now, nature can do a whole lot more than we give it credit for. There have been cultures of Nitrosomonas sp. that were not only living, but thriving under natural conditions with a pH as low as 4.0. Once this miniature ecosystem really gets its gears grinding, it will find a way to keep going. It's the circle of life. The cycle continues.

So while I'm going on about these numbers and "prime growing conditions," just keep in mind that once your aquaponics system is really under way, there is very little that you can do to screw it up. It will find a way with or without you.

Regulating pH, Ammonia, Nitrite, and NitrAte

Now, back to science.

A healthy system is a happy system, so you need to pay careful attention to the chemical concentrations in the water. Purchase a water test kit (available at most aquarium stores) that will give you readings for all four of the above characteristics.

If the water pH is dropping (becoming more acidic), you can raise it by adding:

        Baking soda (sodium bicarbonate)

        Eggshells

        Seashells

        Sodium carbonate

Always change the pH a little at a time. Both fish and nitrifying bacteria are very forgiving when it comes to environmental changes, but they still need time to adjust.

Chapter 3

Types of Aquaponics Systems

Picture a pond with lillypads floating on the surface. At a very basic level, that is an aquaponics system. With that concept in mind, there are three main components to an operataional aquaponics system. Everything else simply makes it more efficient.

        The fish tank

        The vegetation grow beds

        The water pump

Nearly every type of aquaponics system simply combines these elements in a different way. There are dozens of possible variations, from a simple raft floating on the surface of the fish tank to highly complex designs that carefully regulate growing conditions to allow for high densities of fish.

The Raft System

The raft aquaponics system is the most basic type, and is the only type which does not require a pump. Like the lillypads on the pond, a raft system uses styrofoam rafts as the grow beds which float directly on the surface of the fish tank.

The rafts have holes for the roots to trail out into the water, giving them access to the nitrAtes.

The benefit of this system is that it's just so incredibly simple. There is no need for electrical input for a pump, and you can even cultivate some plant species that the fish will eat by themselves. If you're using nature as a reference, this is the most natural type of system available.

Of course, it does have its downsides. First of all, the available area for a grow bed doesn't allow nearly enough plants to efficiently cycle out all the nitrAtes that the volume of water required for the fish will create.

Second of all, the plant roots will be constantly submerged in water, which can create root rot and kill the plants. Therefore, only specific types of plants are able to be grown in this system.

The Continuous Flow System

This type is the next level up the ladder of complexity. The continuous flow system uses a raised grow bed above the level of the fish tank. A pump supplies water to the top of the grow bed, which then trickles down through the grow medium and out a discharge port in the bottom of the grow bed, allowing it to drip back into the fish tank.

Again, the main benefit to this type of system is its simplicity. You don't need any complicated tubing or valves.

The downside, though, is actually the opposite as the raft system: Since the water is continuously flowing through the grow medium, the plant roots often don't have enough time to pull all the nitrAtes out of the water, leading to undernourished plants and an abundance of nitrAte in the fish water.

From a beginner's standpoint, this is the best system to get aquainted with the whole idea of aquaponics, but in terms of efficiency and sustainability it is inherently lacking.

The Ebb and Flow System (Flood and Drain)

In the last two system designs we had to deal with the problem of water flow to the roots. In the raft, there was too much water too much of the time. In the continuous flow, there wasn't enough water at any one time.

The ebb and flow system addresses both of these problems by allowing nitrAte filled water to flood the grow bed, and then drain out completely, giving the roots  a chance to dry off in between cycles.

The ebb and flow system is set up like the continuous flow: Raised grow bed above the fish tank, with a pump sending water from the fish tank to the grow bed. Using a valve system, the water is allowed to reach a certain height within the grow bed, before being released back down into the fish tank.

Of course, this raises the problem of how to automate a system which releases the water from the grow bed after it reaches a certain height. Some people use timers or float valves (such as those used to flush the water in toilet tanks), but I prefer the bell siphon valve (see Chapter 4).

The benefits to an ebb and flow system are that the roots are able to dry off between cycles, decreasing the chance of root rot. Simultaneously, they are given enough time to filter nitrAtes out of the water.

The downsides are of course the added complexity, but also the fact that as the grow bed floods, the water level in the fish tank drops. Depending on the volume of your grow beds, this can become a problem.

The CHIFT PIST System

This is not the most complex aquaponics system you can build, not by far, but it's as far as we're going to go in this book. Once you understand how these few systems work, everything else is just a matter of extrapolating that to meet your own needs. You may have noticed that each additional system only serves to fix an issue inherent in a previous system. After a point it becomes an arms race to find the perfect system.

The CHIFT PIST system is meant to solve the issue of changing water levels in the fish tank. It stands for Constant Height In Fish Tank, Pump In Sump Tank.

There are three tanks used in this system: The fish tank, the grow bed, and a third called a sump tank.

The pump is placed inside the sump tank, which pumps water up into the fish tank. The fish tank has an overflow port at the desired height which runs down into the grow bed. The grow bed uses an ebb and flow system (bell siphon valve), which then drains back down into the sump tank.

This system design allows the water volume in the fish tank to remain constant, which creates a more optimum environment for the fish inside. It also has the added benefit of keeping the pump clear of fish waste and organic matter. When the pump sits inside the fish tank it has to work harder to filter out all the solid waste, which can eventually clog the pump and cause it to stop working.

There's also the benefit that if the power goes out and the pump stops working, the level of water in the fish tank will maintain itself until another power source can be found.

The main downside to this type of system is that the heaviest part of the system, the fish tank, also has to be the highest. The sump tank, the lowest part of the cycle, also has to be able to hold a large volume of water without being too tall.

Chapter 4

The Bell Siphon Valve

In my experience with aquaponics, the most important physical element has been the bell siphon valve. The very first system I built was a continuous flow system. While it worked well, I ran into a lot of the problems I mentioned in the last chapter. The plants grew a sort of yellowish green, showing a lot of the common signs of undernourishment. At the same time, the fish tank water was cloudy and nitrAte levels constantly read high.

I built an ebb and flow system next, but I had never heard of a bell siphon valve so I was having trouble getting the flood and drain cycle to run smoothly. The first thing I tried was a complicated timer system used to open and shut a ball valve, but it used a lot of electricity, and while it never actually happened, I knew that if the timer malfunctioned I'd end up with a flooded grow bed.

So eventually I came across a description of the bell siphon valve.

The idea is that two pipes stand vertically in the grow bed, one with a wider diameter than the other. The wide pipe has a cap at the top end, holes in the bottom end, and stands over the smaller pipe. The smaller pipe runs down through a hole in the bottom of the grow bed.

When the grow bed floods, the water will run into the space between the two pipes through the holes in the bottom of the outer pipe. This inner water height will remain level with the outer water height until it reaches the open top of the inner pipe. Water will then pour down through the inner pipe, pulling the rest of the trapped air down with it.

After all the air is gone, the water flow creates a siphon, pulled down by gravity, which begins sucking water from the grow bed in through the holes in the bottom of the outer pipe.

Once the water drains down to the level of those holes, air gets sucked through as well, breaking the siphon and allowing the grow bed to fill up again. Then, the cycle continues.

Here's a quick visual showing how it works:

You can use this diagram to build your own:

This is an easy enough build, but on the other hand you can also purchase one already assembled at http://www.ebay.com/itm/170888452348

Chapter 5

Types of Fish

The idea of raising fish might seem a bit daunting, especially if you're interested in raising a food crop such as tilapia. Even if you don't have any prior experience, fish are surprisingly easy to maintain, with the most important factor being how much you feed them.

Fortunately, it's even easier to raise fish in an aquaponics system than it is in a regular aquarium, so put those fears behind you and let's take a look at the various types of fish that do well in an aquaponics system.

When you're choosing a species of fish, keep your local climate in mind. Some fish can tolerate cold temperatures, other's can't. Similarly, some species do well in extremely hot climates, while higher temperatures will kill off other species.

Also, and this goes without saying, decide whether you actually want to eat the fish you raise in your aquaponics system. If you're just getting started and don't have any plans for expanding in the near future, you might just want to go with goldfish or koi, since they can adapt to just about any type of water conditions. This gives you a lot of leeway as you're learning the ropes so you don't have to go out and buy more fish every time the pH changes a few notches.

Finally, you may just be limited to what's available in your region or country. Some species of fish can be shipped through the mail, others can't. Different states have rules as to what species are allowed to be kept in captivity so as to lower the chances of some getting loose out in the wild and taking over the local species.

Here's a look at some of the most common fish species used in aquaponics systems. You can use one of these or try something completely new – it's completely up to you.

        Goldfish – One of the more readily available species, goldfish can be found at just about any pet store in the country. They're tough little critters, and they can take a lot of punishment as your system gets up to speed. A lot of people will populate a system with goldfish to get the nitrogen cycle established, and then switch them out for an edible species. Goldfish will also breed in captivity if given some plant coverage inside the tank.

        Koi – Like goldfish, koi are a type of carp that are extremely easy to raise. You'll usually see koi in ponds at Asian restaurants, and they will grow into a variety of beautiful colors. If you're setting up a small aquaponics system as an ornamental piece, koi are the way to go.

        Perch – Perch are omnivorous fish that make a very decent food crop. They don't grow quite as quickly as other fish species, but they can tolerate a wide range of temperatures. Starting from fingerlings, it can take a year to a year and a half to reach a size that's suitable for eating.

        Catfish – There are dozens of different types of catfish that grow in all climates around the world. They're one of the most common farmed species in the US, and they grow extremely quickly. Not only that, but they give you a good return of meat compared to the amount of food

you have to feed them.

        Trout – For aquaponics enthusiasts in cooler climates, trout is definitely the way to go. Their idea growing temperature is between 50º and 65º F. They grow quickly, taste delicious, and fetch a good price on the market. The only difficulty is getting them to breed in captivity.

        Tilapia – Without a doubt the most preferred food crop for aquaponics systems, tilapia grow fast, can withstand a huge amount of stress, and don't taste half bad to boot. Tilapia prefer warm water conditions though, and will grow slowly if the water drops below approximately 70º F.

Stocking Density

Eventually, you're going to run into the issue of how much fish to stock in your system. It's widely recommended to stick with a ratio of half a gallon of water to every inch of fish, although I've seen more thickly stocked tanks that still did well.

The main consideration is that the more fish you have in a tank, the less oxygen there is for each individual. High stocking ratios increase the incidence of disease and slow growth, and overall you just run into more problems the more fish you have packed in there.

If the plant growth is your main concern, even a lightly stocked fish tank can still provide enough nutrients to keep several large grow beds happy. If anything, lean towards fewer fish until you can feel out what your particular system can handle.

I could throw out a bunch of numbers here, but there are plenty of databases where you can find exact stocking numbers for various fish species.

Here's a reference chart for tilapia, but a simple Google search will pull up the same information for any other species.

diagram source: http://www.thefishsite.com/articles/136/tank-culture-of-tilapia

Chapter 6

Types of Plants

I've mentioned it before, but just about any type of small plant will adapt well to an aquaponics system. This obviously excludes trees, so many types of fruits are out, but vegetables, herbs, and spices are all ideal candidates for an aquaponics grow bed.

Leafy greens are your best choices, especially when starting out. Lettuce, spinach, kale, broccoli, cauliflower; herbs such as oregano, thyme, rosemary, basil, sage; and even fruiting bodies like peppers, tomatoes, cucumbers, and squash will all do well in an aquaponics system.

Root crops will also perform well. Carrots, onions, and beetroot are excellent choices, although you might want to leave the potatoes in the ground.

Here's a brief list of some of the plants that I and people I know have grown in aquaponics systems. Keep in mind that this list doesn't even begin to cover all the possibilities, but it should give you a nice starting point for picking out your vegetables:

        Cucumber

        Tomato

        Onion

        Spinach

        Peas

        Lettuce

        Silver beet

        Basil

        Chard

        Parsley

        Watercress

        Bok Choy

        Capsicum (cayenne pepper)

        Celery

        Chilies

        Chives

        Coriander

        Garlic

        Broccoli

        Cabbage

        Egg plant

        Snow peas

        Kohl Rabi

        Butter beans

        Yarrow

        Lemongrass

        Sage

        Mizuna

        Sweet potato

        Rockmelon

        Comfrey

        Carrots

Much of what you grow will depend on the type and size of your system. Most plants, root crops especially, can't be immersed in water 100% of the time. Some plants require deeper root beds than others.

I usually stick with at least 10 inches of grow medium, which allows me to accomodate just about anything. The AquaFlow Aquaponics System that I sell has an 8 inch grow bed, which is perfect for anybody starting out.

Chapter 7

Starting from Seed

One of the questions raised with aquaponics is whether it's viable to start from seed. I had my own doubts about this when I was getting started, since I was worried about the seeds falling down through the grow medium (I use pea gravel) and getting drowned in the water.

It turns out those fears were unfounded, since nearly every seed I've tried to start has come up perfectly. Now I use a combination of seedlings, seeds sown directly into the grow medium, and seeds started on coir pods and then transplanted into the grow medium.

Seedlings

Starting with seedlings is by far the easiest method. Simply take the seedling out of its potting mix and gently shake the soil off the roots in a bucket of water. It's okay to have a bit of soil in your system, but too much and it will leach into the water cycle.

Dig a small hole in the grow medium that will allow you to completely cover the roots, and you're done.

Seeds in Coir

Coir is made from dried coconut husks spun together. It comes in small disks or cubes that you add water to. When starting with coir, allow it to soak for two hours before planting the seeds. Dig about 1/4'' down into the coir and place a seed, then cover it up. In a day or two you'll see a seedling start to sprout, and after about a week (or two, depending on the plant), you can transplant the seedling over the the aquaponic grow bed.

Sowing Seeds Directly

This is by far the easiest method, but the seedlings tend to grow slowly at first. Simply sprinkle seeds out over the grow medium. They will fall down into the cracks, soak up water, and sprout on their own. Once they reach a week or two in age, thin them out to allow six inches per plant.

Staggered Growth Method

To ensure a continuous harvest, try using a combination of seeds and seedlings.

Sow the seeds first. Then, plant the seedlings in the grow medium like normal. During planting you will agitate the grow medium and allow the seeds to drop down off the top layer.

As the seeds begin to grow, they'll be sheltered by the faster growing seedlings above them. When the seedlings reach harvest size, you'll open up the canopy and let the seed-started plants shoot up. Since they've already had time to develop a strong root system, they should grow faster than average.

Aquaponic Growth Rates

I also want to mention the growth rates that can be coaxed out of an aquaponics system. Dr. Nick Savidov, of Alberta Agriculture, Food, and Rural Development in Canada, published a trial which reported up to four times as much plant growth in an aquaponics system as there was in a comparable hydroponics system. That kind of massive, sustainable food growth is exactly what we need right now.

Chapter 8

Types of Grow Medium

Now let's look at the environment in which the plants will be growing – the grow medium. The one fallback from nature in aquaponics (and hydroponics) is that we're removing plants from their natural habitat. Normally plants grow in soil, pulling their nutrients from the water, vitamins, and minerals that naturally reside their.

However, it's much more efficient to provide those nutrients directly, which is why we began developing hydroponic agriculture. The soil provides another benefit though, besides the nutrient levels: It provides support for the root systems.

Erego, we began to look at other forms of loose, airy support that will allow root growth while also permitting water to flow freely in between and reach those roots. As we're about to find out, not all potential grow media are created equally.

Before we look at specific types, let's see what attributes a grow medium should provide for the system.

Grow Media MUST:

        Be Unreactive – A reactive medium will change the pH of the system, which can wreak havoc on both the plants and the fish. Marble and limestone are especially prevalent in some potting mixtures, and the calcium carbonate content of these minerals will raise the pH over time. On the other hand, Hugrozyme, Maidenwell, and Diotamite will lower the pH and make the system more acidic.

        Be Stable – A proper grow medium should never decompose. This will make a complete mess out of the system and create fluctuations in the nutrient levels. Coir, wood chips, soil, and peat moss will all decompose over time, so they are not suitable media for an aquaponics system.

        Be a Reasonable Size – Large rocks create pockets of air which can affect root growth. Tiny media such as sand won't allow enough air – or water – to circulate through the grow bed. Many people still use sand, but I don't personally recommend it.

Most Popular Types of Grow Bed Medium

        Sand – Sand is only on this list because it's readily available and pretty cheap. It's also heavy, messy, and hard to deal with. As I mentioned above, sand can pack itself up pretty tight and restrict the flow of air and water through a system.

        Pea Gravel – This is my medium of choice because it's extremely cheap and provides plenty of aeration throughout the grow bed. The only downside is that it is pretty heavy. If you have a huge grow bed you better make sure it's on a sturdy stand.

        Expanded Clay Pebbles – This seems to be the most popular choice for grow beds, and I personally love it. The only reason I don't use it more is because it can be pretty expensive. It's lightweight, porous, and pretty much the perfect size for any type of root system.

        Vermiculite – This is commonly added to potting soil to add aeration and can be found at most garden centers. It's naturally occurring, lightweight, and chemically inert, which makes it ideal for aquaponics, however, it is also very small, so you need a lot of it to fill a large grow bed.

        Perlite – Perlite is a mineral which has been heated to an extremely high temperature, which causes it to puff out, alot like popcorn. It will hold onto moisture better than any other medium I've come across, and it's probably the lightest of all of them as well.

        Perlite/Vermiculite Combo – I had this recommended to me but haven't tried it yet myself. A 1:1 ratio of perlite and vermiculite is supposed to create a prime grow medium for hydroponic systems, though I haven't personally seen it used in aquaponics systems.

Chapter 9

Homemade Fish Food

In Chapter 1 I made a brief mention about how the only two ongoing expenses in an aquaponics system were the electricity for the pump and the cost of fish food. Some of you will only want to put some minimal time into your aquaponics system, which is perfectly fine, but if you want to go the extra mile and create your own fish food, here's how to do it.

With a large grow operation (several thousand fish), you can expect to spend at least $150 per month feeding everything with commercial fish feed. Even with just a couple hundred fish the cost can creep up to more than $50 per month.

By making your own dry fish food pellets, you can cut that down to around $5 per month, if that. Most of the ingredients will come from your own organic waste around the house – vegetable cuttings, food scraps, etc.

I'm going to use percentages instead of actual quantities so that this recipe can be scaled to whatever size you need.

Ingredients

-75% Food scraps. You can use mostly fish scraps since that's what omnivorous fish would eat in the wild – skin, organs, bones, etc. Worms are also a good addition (Chapter 10 is all about vermicomposting aka raising redworms). Vegetable scraps add extra variety to the food to even out the nutrient content

-25% Flour. Any type of flour works

-Eggs

-Water

-Blender

-Meat grinder

Instructions

1. Blend all the food scraps into a paste in the blender. Add some water if it's too thick.

2. Mix the flour with an egg or two and stir it into the food scraps. You want it to have the consistency of dough. If it's too thick, add water. Too thin, add some more flour.

3. Run the dough through the meat grinder. You might need to adjust the output holes, depending on how big your fish are.

4. The meat grinder will put out long, doughy noodles of fish paste. Put these on a tray and either set it out in the sun or put it in the oven on low. The idea is to get them as dry as possible.

5. Once dry, the noodles will break apart into little fish pellets, which you can then store in an airtight container.

Chapter 10

Vermicomposting

Vermicomposting is the process of raising redworms, also known as red wrigglers. This system uses your own organic garbage as food, and creates rich, nutrient-filled soil as a result, which can be used for gardening. The worms are also useful for fish food, fishing, and anything else you may want to use worms for.

The process is extremely simple. All you need is a bin to hold the worms, some soil, and bedding material. And of course as much organic trash as you want to give them.

Start by preparing the bedding. This can be black and white newspaper, paper towels, old computer paper, or anything that doesn't have too many inks or dyes in it. Tear the bedding into thin strips about an inch wide, and let it soak for a few minutes.

Take it out of the water and wring it with your hands so most of the excess moisture comes out. You really want this to be damp, but not soaking wet. If there's too much moisture the worms can drown, and at the very least they'll migrate to the top of the bin and stop eating.

Start spreading the damp bedding out across the bottom of the bin, filling it about 3/4ths of the way to the top. Fluff it up as you spread it so that enoughy air can circulate through it.

Now take a couple handfuls of soil and spread it out across the top of the bedding. It doesn't matter where you get the soil – your backyard is fine – but if you use a potting mixture make sure it doesn't have fertilizers already added.

Now place the worms down on the top of the soil. They will naturally dig away from light, so leave the lid off the bin for an hour or two until they all burrow down under the top layer. You can buy worms at fishing stores or pet stores; most places will have them, just make sure you ask for redworms. Nightcrawlers are a different type of worm and aren't well suited for vermicomposting.

After all the worms have dug down into the bedding, dig a small hole in one side of the bin and place a pile of food scraps in it, then cover it back up again with more bedding.

A pound of redworms will go through up to four pounds of food in the space of about a week. If the bin begins to smell, it means that you've added too much food. Just stop feeding them for a few days and the smell will go away.

Conclusion

Hopefully this book taught you enough about aquaponics to let you get started with your own system. This is something that anybody can pick up with no prior experience. It's ideal for homes, schools, or even whole communities. At the moment there aren't a lot of people who know about aquaponics, so one of the goals of this book is to spread the word and spark an interest in the general community. Who knows how far we can go with a few motivated individuals with a passion for sustainable agriculture.

If you want to get started with aquaponics right away, you can purchase a full kit by clicking on the link below. I still recommend making the system yourself, but I also understand that it's hard to find the time of day to acquire all the parts and figure out plans for yourself. We live in a busy world, but we should never let that fact stifle our natural urge to excel and push towards a brighter, better future.

Here is the link to purchase the AquaFlow Aquaponics Kit: http://www.ebay.com/itm/170887454361

If you have any questions or wish to offer some of your own advice, you can email me at handleynation@yahoo.com.

I look forward to hearing from you!

Andrew Handley

Table of Contents

Introduction

Chapter 1

Chapter 2

Chapter 3

Chapter 4

Chapter 5

Chapter 6

Chapter 7

Chapter 8

Chapter 9

Chapter 10

Conclusion