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How to Create a Deep Water Culture Aquaponics System

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Written by Sheryl Wiesner   

This hydroponics style system uses no chemical fertilizers, creates no toxic waste to dispose of and is simple to build and operate.

You will be using the system of "Aquaponics" to grow and feed your plants. You raise fish in the deep water culture tank, the fish waste feeds the roots of the plants and in turn keeps the water clean and safe for the fish. Once set up and cycled you should only need to top off the water and perhaps do the occasional partial water change.

The great thing is that you eat the plants and the fish!!! What could be more natural???

Things You'll Need:

β€’ 20 gallon rubbermaid tote with lid.
β€’ 11 2 or 3 inch net pots available online or in hydroponics stores.
β€’ 1 & 7/8 inch hole saw for the 2 inch pots or a 2 & 7/8 inch hole saw for the 3 inch pots
β€’ cordless drill to fit the hole saw.
β€’ aquarium air pump with tubing and airstone.
β€’ dechlor from the pet store
β€’ Optional, "Cycle" beneficial bacteria sold in most pet stores. Can also some use aged fishtank water or pond water instead to get the bacteria going.
β€’ all purpose gravel or hydroten for the net pots
β€’ small amount of washed gravel for the bottom of the fishtank AKA resivoir
β€’ 2 channel catfish from the pet store
β€’ Nitrate/Nitrite test strips you can find these at the pet store.
β€’ Optional small aquarium pump about 50 gph to increase water circulation.
β€’ plant seedlings with enough root growth to go thru bottom of net pot.
β€’ aquarium sealant
β€’ Optional weatherstripping

1. Step 1
Obtain supply's and determine where you are going to set up your system. Set up supplemental lighting if necessary. You can make a simple grow light using a fluorescent shop light and then use one cool white and one warm white bulb in the fixture... no need for expensive grow lights.

2. Step 2

This is an 18 gal Rubbermaid. This lid required me to get a little creative as it is not uniformly flat. I also had to invert it for the plants to reach the nutrient solution, AKA fishwater.

Determine how many holes and what pattern you will use before you begin cutting with the hole saw. Lids are different some are nice and flat or like the one in the picture some have contours you will have to work around. A good rule of thump is for small plants space 3 inches or so apart.
For this example we are going to cut 3 rows of 4 holes each.

3. Step 3

12 holes were cut into the lid of this tote, one is for the cord to the pump, airline with airstone and to use to feed your fish.

Mark the top side of the lid where you are going to make your holes, don't get fancy here just put a dot where the drill bit should be. Put the lid on the tub and make your cuts using an appropriate sized hole saw. You are going to cut 12 holes. You should have 3 rows of 4 holes each, you may want to offset the center set of holes to give the plants more room.

4. Step 4

Place a small layer of well washed pea gravel on the bottom of the tank, this will collect the heavy solids of the fish waste giving it time to decompose and will also help keep your pump clean if you choose to use a pump for circulation.

5. Step 5

Attach airstone to airline tubing and attach tubing to the air pump.

If you live in an area with frequent power outages you may want to install a check valve into the airline to prevent water from flowing back into the air pump in a power failure.

If you place the pump above the level of the water you wont need to do this. place the airstone into the tub using one of the holes you cut near an edge, this hole will hold all cords and be the port where you will feed your fish from.

(Optional) Insert pump into tank and exit cord thru the same hole as above.

6. Step 6

Some rubber maid style tubs have ventilation holes in the handle area on the sides of the tub. If so then you need to take a small amount of aquarium sealant and fill the holes. Allow time for it to dry thoroughly before you add any water to the tank.

7. Step 7

This lid needs to be inverted for the plants to reach the water. In a case like this you need to do the weatherstripping as in step 7.

If the tub you are using has a deep lid or irregularly shaped lid you will need to invert the lid for your plants to reach the water.

Apply weather stripping around top edge of rubber maid tub.

Use extra care to insure that you do NOT stretch the weather stripping while you are applying it to the tub, if it stretches it will pull loose and not make a nice tight fit when you close the lid.

8. Step 8

Place tub where it will be operating and fill with water. Add the Dechlor according to bottle directions. If you have an aquarium or pond that has been set up and running for a while you can add a gallon or two of this water to the tub to speed up the nitrogen cycle process. If not you can add a product called "cycle" which provides the beneficial bacteria that changes fish waste into plant food.

9. Step 9

plug in air pump and water pump if used. If you have warm water fishes like Tilapia you will need a small wattage heater. This is not necessary for Catfish, Perch, Bass or Bluegill. If a heater is used set it to 78-82 degrees, DO NOT PLUG IN HEATER UNTIL AFTER IT HAS BEEN IN THE WATER FOR AT LEAST AN HOUR!!!!

10. Step 10

Wait 24 hours for the water peramiters to settle before adding your fish. You can stock at a rate of 1 inch of fish for every gallon of water, some fishes can tolerate higher stocking densities as long as the water remains nontoxic to them.

Float the bag of fish in the rubbermaid tub for at least 20 minutes before releasing the fish into the tub. Put the lid on the system to keep the fish from spooking and jumping out.

11. Step 11

If the plants you are going to use are planted in some sort of soil you will want to gently wash it off of the roots of your plants.

Once this is done you will place the roots into a pot and gently tease some thru the holes in the pot so that they can dangle down into the water. Gently add well washed pea gravel or hydroten to the pot to stabilize the plant and keep it from falling over. Then place plant in pot into a hole in the lid and repeat untill all plants are in the lid.

12. Step 12

Test the water daily for the first 6 weeks for Nitrate/Nitrite and do partial water changes as needed. After the first 6 weeks test weekly and do water changes as needed.

If you have your fish to plant ratio correct you will not need to do any water change after the first 6 weeks or so.

13. Step 13

If supplimental lighting is needed set it up now, lights should be on timers set for 16-18 hours a day.

Remember you do NOT need expensive grow lights, one cool white and one warm white bulb are all that is needed.

14. Step 14

In about 6-9 months your fish should be big enough to eat and you can start the system over or just keep fewer big fish in the tubs.

Sit back and enjoy the freshest fish and produce that was grown without dangerous chemicals and fertilizers that damage the environment.

Water changed out of the system can safely be used to water other plants in your house and yard without fear of causing ecological damage.

Tips & Warnings

β€’ for larger plants you will need 5 or more inches of space around the pots.
β€’ Also if you are doing really large plants you may only get one or two in each container, please use pots that are appropriate for the size of your plants, the pots do not support the roots but they keep the plant upright, too big of a plant in too small of a pot will topple.
β€’ You will always make the holes for the pots slightly smaller than the pots themselves this way the pots wont fall thru the lid and into the system.
β€’ Some fish like Tilapia, Goldfish and Koi are vegetarian and if you forget to feed them they may eat all of your plant roots, this is why I recomend Catfish, Perch or Bass for this type of system.
β€’ Use extra caution while using the hole saw, I found that sometimes it bounces out during the first part of the cut and you could get hurt, I got my left hand, not bad but it did get me!
β€’ Never let children use power tools!
β€’ If a heater is used DO NOT PLUG IN HEATER UNTIL AFTER IT HAS BEEN IN THE WATER FOR AT LEAST AN HOUR!!!! Heaters have been known to explode if you plug it in too soon. Also do not ever let an aquarium heater run when there is no water!

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