A Simple DIY Hydroponic System

The Indoor Version

Indoor hydroponics are a fun, eco-friendly way to enjoy a garden without a yard. With this system, you can have a highly productive urban garden with just a few square feet and minimal cost. Your hydroponic fruits and vegetables will be vibrant, healthy, and taste great. If you love gardening, give this hydroponic system a try. You'll love it.

The system we're about to build is a water culture. Your plants' roots will grow directly into the nutrient solution. It's pretty cool to see. As long as a small part of the roots are exposed to air and the solution is well oxygenated, there's no such thing as overwatering. It's simple, inexpensive, and highly effective. It works great with all kinds of plants. Tomatoes, strawberries, herbs, and many other vegetables thrive with minimal effort.

Supplies

Name Purpose Price Link Description
Sterilite 25 Qt Shelf Tote Container $17 Amazon Buy.com Be sure to choose an opaque container to hold the system
Ecogrow Nutrient Nutrient $7 Ecogrow A balanced nutrient suitable for almost any plant
10x 2" Mesh Baskets Plant Support $4 Amazon Mesh baskets anchor the plants in the nutrient solution
10x 1.5" Rockwool Cubes Growing Medium $6 Amazon Rockwool supplies air, water, and nutrient to roots
60 GPH Fountain Pump Water Aeration $19 Amazon A small pump to circulate and aerate the nutrient solution
Black 1/2" Flexible Tubing Flexible Tubing $5 Home Depot stores Provides nutrient flow
2' T5 Fluorescent Light Light $95 Amazon T5 fluorescent light is efficient and inexpensive
Appliance Timer Lighting Control $8 Amazon Plants need a regular cycle of light and dark to be happy
System Cost: $161

Measurement Tools

Name Purpose Price Link Description
pH Control Kit pH Control $15 Amazon Proper pH lets plants use nutrients efficiently
TDS Meter Nutrient Meter $16 Amazon Allows you to monitor the nutrient level

Little Helpers

Name Purpose
Zip Ties Tie components down to the container
Cardboard Reflector backing
Aluminum Foil Reflector surface
Tape Attach foil to the reflector backing
Plastic Wrap Keeps seedlings moist
Drill (optional) Make small holes in container lid
Knife, exacto knife, or box cutter Cut holes in lid.

Construction

Fig 2. lid with holes outlined

Prepare the Container

You only need to modify the container's lid. Leave the rest of the container unmodified to keep it watertight. Be careful as you're cutting! Don't do anything you don't think is safe. You'll be making holes in the lid for:

Fig 3. a mounted basket

Cut each plant basket hole just slightly smaller than the lip of the basket. The basket should rest in the hole supported only by its lip. If your holes are too big, you can poke nails through the basket to hold it in the lid.

Fig 4. access hatch construction

The access hatch should be large enough for you to easily fit your hand inside. Make a fist and hold it against the lid. Draw a rectangle slightly larger than your fist's outline and cut it out completely. Reattach the lid using zip ties threaded through small holes (use a drill or rotate your knife tip in the lid to make small holes).

The pump will be right next to the access hatch so it's easy to maintain. Cut two tube-sized holes: one just above the pump, and one on the other side of the container. A drill with a 1/2 inch bit is ideal for this, but a knife will work too.

Prepare the Nutrient

Before you prepare the nutrient solution, place the container where you want to keep it. It's tricky to move when it's full.

Fill the container almost completely with tap water, leaving an inch or two of space at the top. This will be 5 to 6 gallons of water. Check the Total Dissolved Solids (TDS) of your water with the TDS meter. It should be under 100 PPM (Parts Per Million). If it's more, use distilled water instead. You're shooting for a nutrient concentration of 500 PPM, excluding whatever's in your tap water already. Adding 5 to 6 teaspons of nutrient (one tsp per gallon) should do the trick. The nutrient won't dissolve immediately, but don't worry! Within a day your solution will be close to 500 PPM. Use your TDS Meter to double check.

Fig 5. plant, rockwool, basket, and nutrient level

Construct and Install the Plant Baskets

For each plant basket, stuff a rockwool cube in as far as you can and drop a few seeds on top. Be careful! The rockwool is like fiberglass, so use rubber gloves to protect your hands. Moisten the rockwool with nutrient and cover the top of the rockwool with plastic wrap until the plants sprout. It's essential that the rockwool stays moist until your plants' roots reach the nutrient solution. If the nutrient level is below the rockwool, you can put a loop of string between the rockwool and the nutrient to keep it moist.

Fig 6. the pump setup

Install the Pump

Mount the pump below the tube hole closest to the access hatch and attach it to the tube. Pass the tube up through the first hole and down through the second. Use zip ties to stabilize the far end of the tube. You want the tube to end just under the level of the lid so the stream mixes air into the nutrient solution when it hits the surface. The pump is there to keep the water circulating and for aeration.

Fig 7. the light mount

Mount the Light

Mount the light about 8 inches above the grow surface. Use zip ties or string to secure it in a way that makes it easy to raise the light as your plants grow. You always want the light at least an inch above your plants' tallest leaves.

Connect and Configure the Timer

Set up your timer to be on for 16 hours during the day and off for 8 hours during the night. Plug your light into the timer. Plug your pump directly into the outlet, you want it to run all the time.

Fig 8. the reflector setup

Build Reflectors

You're almost done! You have a sweet setup, but let's get everything we can out of the energy your light is pumping out. Use cardboard from boxes and aluminum foil (shiny side out) to build an inexpensive light reflector. Enclose your grow area completely in reflectors for maximum efficiency.

Ongoing Care

It's time to kick back and watch your plants flourish. With minimal care, they'll grow several times faster and larger than plants grown in soil.

The Nutrient

Add water as your plants use the nutrient solution up. You can use the TDS meter to ensure the nutrient level stays at 500 PPM. If it sinks, add a teaspoon of nutrient for every 100 PPM it has fallen. If it rises, add more water. Every month, empty the nutrient solution completely. This clears out any nutrient imbalances that have built up. You can use some of your tubing as a siphon to easily empty your container.

The Plants

Some plants like tomatoes and basil need regular trimming to keep them small and productive. Don't feel bad about trimming off their main shoot, they'll grow back fast. Strawberries grow runners, so cut those off to help the plant focus on fruit production. If you have flowering plants, you'll need to pollinate them to produce fruits. Just tap the flowers, the pollen will take care of the rest.

Happy Growing!