Difference Between Hydroponics and Aquaponics Part 3

Aquaponics Design

Aquaponics systems have expanded to a variety of designs over the years. Still, every aquaponics design is going to be structured with 3 basic components:

  • A grow bed for the plants
  • Water tank for the fish
  • A water pump or some other plumbing design that moves the water from grow bed(s) to and from the fish tank, such as gravity

 

We will cover the various aquaponics system designs most often used, but first lets go over the grow beds filled with media where plants are raised.

 Media Filled Grow Beds 

Flood and Drain Aquaponics

A media filled grow bed comes in just about all sizes and shapes depending on the system type  in use. In this image, a container of 30 X 24 inches  is typically filled with media to within 2 inches of the top of a 6-12 inch deep container. There are several aquaponics media options to choose from but Hydroton is our favorite.  The pipe on the left is pouring water continuously over the media of Hydroton pebbles that is pumped in from the fish tank.

The Hydroton media is a self-contained biofilter because the surface of the porous pebbles of clay,  provide a home for the bacteria to grow. This in turn becomes the rich nutrients that the plants feed on.

This type of grow bed is more useful for hobbyists and homeowners. Other systems such as Nutrient Film Technique and Deep Water Culture systems, use trays (rafts) and netting cups as a bed for raising plants . These are very effective “backyard” systems too, and I’ll go over them in detail  later.

Media filled grow beds  will need to be sturdy enough to hold the weight of pebble media and water. Holes need to be drilled on the side of the bed and fish tank to accommodate pipes that run water in and out of these containers. Most growers will use PVC fittings, plastic washers, and silicon caulking to properly waterproof the pipe-to-container connections.

This size of grow bed container means more media in the bin, which results in more bacteria growth. Since the bacteria converts the ammonia to nitrates and ultimately nutrients that the plants feed on, more fish can be added to the aquaponic tank.

The grow bed container will need water trickling over the media to keep the roots of plants moist. This is usually done by installing a water pump, though smaller systems can be designed using plumbing pipes angled to let gravity do the work. So it really depends on the type and size of aquaponics system you choose to build. I’ll over all the basics of Aquaponics systems being used so you can compare them with which setup will work best for you.

IBC Aquaponics Grow Beds

 

ibc tote aquaponics

One type of media grow bed that is often  used is the IBC aquaponics container tote. Typically,  gardeners building an aquaponics system, will purchase an IBC tote and convert it into an a media filled grow bed and an aquaponics tank for fish. They do this by first cutting the bars of the outside cage and then the Intermediate Bulk Container itself. This leaves two containers, typically 25% height for the grow bed and the remaining 75% for the aquaponic fish tank.

The top section of the IBC is turned upside down becoming a grow media container for the plants. The larger part serves as the fish container. A submersible pump sends the water into the grow bed through a plumbing system. (usually of PVC). 

Aquaponics System Types Most Used

1. DIY Deep Water Culture System

backyard pond

The Deep Water Culture  Aquaponics design, also known as Raft or Floating Systems, go way back in the history of aquaponics. The Ancient civilizations of Aztecs and Asian cultures grew their vegetables on rafts floating in ponds and swamp-like environments (image above). It eventually developed into hydroponic systems, and more recently Aquaponics Systems.

As mentioned in our summary from  Aquaponics Grow Bed, this system is light on maintenance and best for leafy fast growing vegetables with small root systems. The components we use most are for small to medium systems that are suitable for hobbyists and home-based growers, as opposed to commercial systems that require more space and expensive equipment. But both have their benefits and and are capable of wonderful produce harvests.

 

Like other types of aquaponic systems, DWC requires routine management to keep plants, fish, and the bacteria population in good health. Unlike ebb and flow systems, draining water from the grow beds aren’t needed. Two basic types of DWC systems are in use, both with plenty of modifications design out there.

1. The Float Tank. This uses grow beds of Styrofoam insulation rafts that float on top of a tank filled with fish. Plants grow in net pots that are placed in holes in the Styrofoam allowing the roots to dangle in the water continuously. This simple design can be used indoor,outdoor, and even backyard ponds

using tanks, aquariums 

2. The Canal System. This is similar to the other but a little bit more complex. The fish tanks are separated from the grow beds that are canal channels or troughs. Some growers use big ibc aquaponics totes that we went over earlier in this article.
Each trough or channel has its own deep water culture water level. It’s also different in that submersible pumps are used to deliver water to the grow beds from the fish tanks. It’s a larger system than the Float Tank version and circulates the water more efficiently. It is used successfully by commercial growers and is a promising method for sustainable solutions regarding global food issues. Some growers use the bucket system we went over in  diy deep water culture bucket system, but they seem to require more manual management, particularly with the fish tank component.

A Filter(s) is placed between the fish tank and the grow beds in the larger systems like the Canal Type. Included but not always used are,  swirl filters, nitrafication filters, screens or reverse osmosis filters, and waste solids filters. Be advised that the solids will require manual cleaning weekly.

The fish tank supplies not only the fish, but also their waste that is ultimately converted to nitrates that the plant roots absorb as nutrients. The fish waste excrement becomes ammonia that goes through a conversion to nutrients thanks to colonies of bacteria that live on the surface area of the tank- If you want to learn more about how this process works go to our article Aquaponics Biofilter Essentials

Deep Water Culture Tips

The fish tanks should include a device that aerates the water. Airstones or external pumps work well creating bubbles of air that help to increase the oxygen levels.

The water in the system needs to be tested routinely to:

1. Be sure the pH is at proper levels

2. Confirm the water temperature is stable

3. Verify that the nitrification procedure is in order

It’s also a good idea to check that pumps are working properly and the tube or pipe network is in good condition. It’s important to clean out any excess material that gets in the filters or blockage may clog the system.

Aquaponics Components Needed for Deep Water Culture Systems

  • Canal or Troughs- Grow beds for holding the plants and water pumped in from the fish tank. Several of these containers can be used depending on the space available, and how much produce you want to grow.
  • Float or Raft Grow Beds- made of some type of foam for the plants to reside while floating on the fish tank unit. Holes in the raft allow the plant roots to be constantly suspended in the water below.
  • Fish Tank- This is where the fish live as well as the bacteria that acts as a biofilter and converts fish waste to nutrients for that plants.
  • Filters- Several types can be utilized between the grow bed(s) and the fish tank to keep the system efficient, clean and healthy.
  • Water Pump- Used in the Canal System to pump water from fish tank, through any filters that are deployed, into the canal channels, and also used to recirculate the water through the system
  • Aeration Device- Airstones with external pump are recommended

Types of Crops That Do Best

  • Lettuce (all types)
  • Swiss Chard
  • Bok Choy
  • Collard Greens
  • Sorrel
  • Kale
  • Okra

 

2. NFT Aquaponics System (Nutrient Film Technique)

The NFT Aquaponics design comes from Hydroponics systems where they were originally developed. Now they’ve been adapted to aquaponics systems with the main difference being the addition of a fish tank component. There are many benefits that come from using this type of system, but planning ahead is recommended to avoid any problems that may come along.

How Does NFT Work

Water is distributed through the system by 2 forces, a submersible pump and then gravitation. The plants grow in channels similar to gutter downspouts you find on buildings. You can also use PVC pipes up to 4 inches in diameter that are usually 4-6 feet in length. Rectangular shaped pipes are popular with growers because of increased space for the roots on the flat surface bottom.

aquaponic garden design

 

The plants grow in net pots placed in holes cut on the sides of the channels (image above). The roots dangle below inside the channel avoiding light. There is no grow media in the pots which means no bacteria biofilter to breakdown the fish waste. More on Biofilters below.

 

The pump forces a constant flow of water upward into the channel’s inlet. From there the water gravitates down the channel that is at a slight downward angle, and provides moisture to the plant roots. This is a very thin flow of water, but that leaves plenty of space for needed oxygen and helps to avoid any clogging in the system.

The submersible pump is usually placed into a water tank with the fish. That means the toxic ammonia from the fish waste will be in there with it. As I pointed out above, there is no bacteria biofilter in the channel’s, so you’ll need a separate filtration device to handle the waste solids. The pumped water will flow through this device before heading up to the channel inlets. This type of biofilter will be a container with media that provides an environment that bacteria can populate and convert the waste into nutrients for the plants.

Benefits of Nutrient Film Technique Systems

The NFT systems has many of the Ebb and Flow advantages without having to use bell siphons and timers. 6 more advantageous perks that come to mind:

  1. Simple to Build- NFT is fairly easy to setup without needing a lot of additional components. The gutters or channels can be installed quickly, and the pipes and tubes of plumbing are few compared to other systems, and take up less space. 
  2. Significantly Oxidated Roots-The way the NFT design is crafted, a portion of plant roots remain above the water level continuously. This enables the roots to take in oxygen while expelling waste gases. This way the plants won’t drown in excess water and nutrient rich water is always accessible.
  3. No Need for Grow Media-This is the case for most NFT systems because the plants are placed in net pots inserted deep enough into the cutout sockets so that the roots are never in contact with light. They are always dangling in the water though, and do not require media and bacteria conversion because the pump is supplying a continuous flow of nutrient-filled water.
  4. Continuous Water Flow- Constant flow prevents stagnancy in the water keeping fungus and algae at bay while plants stay healthy with non stop water availability.
  5. Gravity Conserves Energy-The grow trays are positioned at a sloping angle meaning high powered pumps aren’t necessary. Also, the water pours into the reservoir below, keeping it relatively cold, so eliminating the need for a water chiller device. Because of the design of these 2 components, a significant amount of energy and money are saved.
  6. Easy to Monitor the Roots Condition- The channels are shallow and have no grow media making it easy to monitor how the roots are growing. This way you can avert any disease development before it spreads.

NFT Problems

Most problems in a NFT system can be averted by good planning ahead of time. If plants are looking stunted or injured it may be caused from temperature issues, over exposure to lighting, access to nutrient solution, or just poor support of the plant. The key is to stay in front of these problems so you can fix it before it gets out of hand. Routinely monitoring and consistent maintenance is important.

The absence of grow media can make it more difficult to stabilize root temperature. This can be averted by focusing on quality insulation and temperature regulation.

Keep an eye on the water pump. If it stops and you’re away for the day you could lose the entire crop. Keep the channels clean from clogging of debris such as waste solids and overgrown root hairs. Clogging can cause the water to back up and drown the plants.

NFT systems are designed primarily for leafy vegetables with small root areas. These plant types will grow amazingly fast with healthy practices. Best vegetable plants for nft aquaponics system include:

Basil
Cilantro
Romaine, Butterhead, Bibb, Boston, Looseleaf Lettuce
Kale
Mint
Oregano
Italian Parsley
Sage
Swiss Chard

We will continue to Aquaponics System #4 in our Difference Between Hydroponics and Aquaponics Part 4