Steve Pond - Aquaponics Systems for the Freshwater Tropical Fish Keeper

Aquaponics Systems for the Freshwater Tropical Fish Keeper

by Steve Pond

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Copyright 2013 Steve Pond

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First published 2013

Printed in the United States

Table of Contents

1. Introduction

Aquaponics is the joining of two living systems much as they occur in nature - interweaving the two systems provides massive benefits to both environments and you benefit greatly because of it.

Aquaponics combines the rearing of fish in an aquarium with the growing of live plants outside the aquariu m. Each provides for the needs of the other.

Her e s how it works:

You feed the fish properly...

The successful system then provides:

Crystal clean water and plenty of dissolved oxygen for fish.

Water, air, and enough of the proper nutrients for plants.

Essentially what you do with an aquaponic system is to extend your use of a biological filter to remove also nitrates and mineral type deposits that commonly cause the need for water changes.

The addition of an "aquaponic filter" will allow you to grow a wide variety of plants while providing clea n, crystal clear water for the fish.

When set-up appropriately, even a 2 foot fish tank will easily grow a variety of vibrant plant life.

You can enjoy nutritious, organic vegetables and herbs and beautiful plants along with freedom from water changes.

This book focuses on a multitude of ways that an existing home aquarium can be adapted to an aquaponic filter.

We are, first and foremost, aquarists. We enjoy keeping freshwater aquariums and watching our fish as they swi m.

By the end of this book you will know how to incorporate the needs of growing plants and raising healthy vibrant fish in an integrated system that fully provides the needs of both.

2. Understanding Nitrate

All living organisms need adequate moisture and a suitable and healthy habitat to grow. The common denominator between the fish and growing plants is nitrate - NO3. An aquatic environment will create large amounts of it - especially if the system is closed like an aquarium. The plants need it as the fundamental building block to grow and thrive. The fish will become weak and diseased if it concentrates in their home to high levels.

The classic way to remove nitrate from an aquarium, at least for the past 50 years we have been keeping fish, has been to dilute it. The two main reasons a partial water change must be done on a regular basis are:

1) dilute the nitrate produced by the biological filter
2) maintain steady water conditions by diluting other chemical build-ups such as carbonate and other hardness minerals that remain in the water after evaporation.

Until I found aquaponics as a filter, there was not a reliable way to remove the nitrate from the closed aquarium easily, or without considerable effort. There are resins and all kinds of devices that will remove some, but nothing reliable or safe for the fish. In most previous methodologies a part of the system needed to be turned anaerobic - deprived of oxygen. Certain bacteria do remove nitrate that way. The problem is that all sorts of noxious gases are produced. These can harm the fish if released accidentally.

We view aquaponics as a filter for an aquarium. Commercial aquaponics simply uses the aquarium as the production factory for the nitrate needed by the plants. The plants, in turn remove the nitrate and return purified water to the fishes habitat. Our job is to design a system that will deliver nitrate produced in the aquarium to the roots of the plants. The roots suck the nitrate into the plant as fertilizer. Purified water is returned to the aquarium.

It doesn't really matter where your focus is, on growing an organic garden or keeping the fish in the best health they have ever known. The combination of the two is a powerful system that produces astounding result s .

3. What aquarists need to know about soil-less indoor gardening

The needs of the plants:
air
water
rooting substrate
nutrients

Air - Plants require oxygen and carbon dioxide. Both are components in the water where fish swim. Carbon dioxide is used during photosynthesis and is combined with other elements to form sugars, usually in the leaves of the plant. During this process oxygen is produced.

When light is not available, the process is reversed. Like other lifeforms, the plants require oxygen and will then give off carbon dioxide. Unlike an aquatic plant, however, there is no lack of oxygen in the atmosphere.

There is no oxygen deprivation possible during the late evening, which can be the case with a heavily overgrown aquarium with lots of strong aquatic plants. Morning kill is the result of a heavily planted fish tank demanding so much oxygen during the very early morning that the fish are suffocated.

Over-planted tanks may use most of the nitrate created in a tank, but will usually require added carbon dioxide to be infused and possibly even an air pump to break the surface and allow oxygen to enter to prevent morning kill.

Water - One of the most common pieces of advice I offer to new aquarists is not to waste the water when a partial water change is performed. The [dirty] water from an aquarium has lots of trace elements, especially nitrate, in it.

It is a wonderful elixir for houseplants. Instead of pouring the dirty water in the bucket down the toilet, it should be spread over the home's live plants to help them grow strong. The magic is that the solution contains great fertilizers and other trace elements that plants require. Plain water will keep a plant alive, but used fish water will make them thrive.

Delivering the "dirty" water to the roots of plants on a regular basis will do a number of things. The main one being to provide an ongoing source of nutrients to the plants. There are a number of ways to do this. Later in the book we will describe some of the most effective ways aquaponics can deliver water and vital nutrients to food plants you want to encourage.

Rooting Substrate - almost every plant has some form of root structure. The only exception to this is algae, which are found in bodies of water. In the aquarium situation, these compete with rooted plants for valuable nutrients. Land based plants require a substrate to root themselves and provide a way to stabilize the plant as it grows. Most standard gardening methods use the earth to root plants. Then the nutrients are supplemented over time with chemically based fertilizers to make the growing medium stronger and more supportive for the plants being grown.

Aquaponic and hydroponic grow beds also need to provide a substrate for the roots to use to stabilize the plants. There are quite a variety of mediums used. We will discuss the one we find to be the best a little later in the book. Sometimes the substrate will add trace elements, other times the selected medium is inert and simply provides a location for the roots to gain a strong foothold to keep the plant upright and properly oriented.