by Ed Rosenthal
4.Place rope in containers. Tape or glue in place. Once the medium is added it won't move.
5.Fill containers with planting medium.
6.Place containers on supports. Make sure the wicks hang down to the bottom of the water tray.
7.Fill the tray with nutrient-water mix.
8.Water the containers from the top to get started. Make sure the planting medium and wicks are thoroughly moistened.
9.Mix nutrient/water solution and adjust it using meters to test the EC or ppm and pH of the solution.
10.Add a small submersible pump in the tray to circulate the water in the tray.
11.If the room temperature gets cool, it may cool the water too much. Add an aquarium heater to the tray.
12.Use a sheet of white/black polyethylene or other opaque cover to place over the tray. The cover keeps light from getting into the nutrient/water solution, where it would promote algae growth.
13.Optional Accessories—Water Reservoir regulated by a Float Valve. The water level of this system should be maintained at a fairly stable level. As the plants grow they will use larger quantities of water so it will have to be replaced more frequently as the garden proceeds towards flowering.
EQUIPMENT
•One tray
•Support for containers—pallet, cement blocks, wood block wire trays
•Appropriate diameter nylon rope
•Planting containers
•Tape or glue
•Planting mix
•pH test meter or pH test paper
•Hydroponic Nutrient Solution
•EC or ppm meter
•Submersible pump
•Aquarium heater
•Tray cover
•Reservoir (optional)
•Float valve (optional)
CAPILLARY MATS
Capillary mats are about a quarter inch (0.6 cm) thick. They are made from soft polyester covered with opaque polyethylene perforated with small holes. They have great wicking ability and are used in sub-irrigation systems. When containers are placed on the mat it compresses. This indent is below the level water travels.
The media draws water only as needed; the water requirements of different size plants on the same mat are met without under or overwatering individual containers.
A table is covered with polyethylene plastic to create a water barrier. It has a slight slope, about 2.5%, 1" per 40" (2.5 cm per 100 cm). Place the capillary mat over it. Make sure the containers have drainage holes on the bottom. The water in the mat puddles around the depression made by the container and is drawn through the media by capillary action, in the same way a tissue draws up water.
Capillary mats: water gathers in the indent made by the container in the fabric. The containers wick up water as needed.
This system is used in large greenhouses because it is easy to set up and is very reliable.
There are several ways to keep the mats water filled. The easiest is to have it draw water from a reservoir that it drapes into. Another method is to use a small pump to deliver water from a reservoir. The water flows through the mat and drips back into the reservoir.
Capillary mats are effective in irrigating containers up to about ten inches (25 cm) high. They are simple to maintain and a very efficient method of using both nutrient and fertilizers.
DEEP WATER CULTURE (DWC)
DWC systems keep the roots bathed in an oxygenated water/nutrient solution. The system consists of a submerged container that holds the plant stem in place above the water level. The roots hang down into the oxygenated water. The roots have total access to water, nutrients and oxygen, which is dissolved in the water. This promotes extremely fast growth and high yields.
Plants thrive in this type of unit because it allows them easy access to nutrients. Active hydroponics systems oxygenate the roots through constant air circulation. The Under Current by Current Culture mixes nutrients with oxygenated water and circulates the solution under the roots throughout all the buckets.
DWC systems require sensitivity to the plants on the part of the grower. Unlike planting mixes that buffer nutrient imbalances, the DWC environment is instantly affected by changes to the water. The result of these changes, helpful or harmful, become apparent very quickly. Experienced gardeners can “read the plant” to determine its health and needs.
The common denominator of all DWCs is a container that holds water that the roots hang down into. A container holds a hydroponic planting medium such as clay pellets or rockwool cubes over the water. The reservoir water/nutrient solution is aerated using airstone bubblers, circulaing water or a waterfall.
DWC systems are manufactured as stand alone containers, as well as sets attached to a central reservoir. Other models circulate the water using tubes that connect the containers to each other. The plants are held in held in small containers above the water.
BUILDING A DWC BUCKET
Use a three– to five–gallon bucket. Measure its diameter. Most standard buckets are 11½" (29.2 cm) wide.
1.Use a hard plastic flowerpot drain tray that fits over the bucket.
2.Use a 6-8" (15-20 cm) ribbed container to hold the planting medium.
3.Using a pair of clippers or a saber saw cut a hole in the tray large enough to let the ribbed pot fit firmly inside. Drill a hole in the tray large enough to allow ¼-inch (0.6 cm) air tube to slide through.
4.Slide the tubing through the hole in the tray. Attach an air stone to the tubing that is going into the container. Attach a small air pump to the other end of the tubing.
5.Place a small fish tank heater set at 70° F (21° C) inside the container.
6.Fit the tray onto the container. Place the ribbed pot into the tray. Fill with LECA.
7.Add water leaving about four inches (10 cm) for air. Plug in bubbler and heater
EQUIPMENT
•3-5 gallon (11-19 L) bucket
•Hard plastic plowerpot tray
•6-8” (15-20 cm) ribbed container
•Air pump
•¼” (.63 cm) tubing
•Airstone
•Fish tank heater
•LECA
EBB AND FLOW SYSTEMS (FLOOD SYSTEMS)
Ebb and flow are the systems that most people think of when hydroponics is mentioned. The containers or rockwool cubes are held in a tray. Its depth varies depending on the containers’ height. Water is periodically pumped to the tray. The planting medium holds enough moisture between irrigations to meet the needs of the plant.
Ebb and flow systems are easy to construct, promote vigorous growth, and their maintenance is fairly carefree. They can be used to irrigate rockwool cubes or any of the hydroponic planting mediums.
BUILDING AN EBB AND FLOW SYSTEM
1.To construct simple manual ebb and flow system use a tray about 6” (15 cm) deep. Attach a flexible ½-1" (1.25-2.5 cm) tube to the one of the sides at the bottom. This tube will be the drain.
2.Fill 8” (20 cm) tall planting containers with one of the recommended hydroponic mediums and place them in the tray.
3.Rockwool can also be used. If you are growing small plants just use 4” (10 cm) cubes. If the plants are to be larger place a rockwool slab down first and set the cube on top.
DWC systems promote lush root growth.
4.To water, hold the tube above the tray so it doesn’t drip. Pour the water from the container into the tray. Then place the tube below the tray so the water drains into the container.
5.If you use LECA, the first time fill the tray 4” deep with water and let it stand. If you are using LECA leave 1-1½" (2.5-3.75 cm) of water in the tray. LECA doesn’t hold much water but it readily wicks it up as it is needed. If you use coir, peat moss, a peat blend or vermiculite-perlite, fill it 3” (7.5 cm) deep and with 4” (10 cm) rockwool flood only to 2” (5 cm). Add more to maintain the level until the medium is saturated. Drain it into the container using the flexible tube. This is the more than the maximum amount of water/nutrient solution that will be need
ed each time the plants are watered. Not as much drains back in as was poured out; some water is retained by the medium. Garden irrigation needs differ because of planting medium, garden temperature and the size of the plants. If the medium feels moist the plants do not require irrigation. A more scientific way of determining whether the plants need irrigation is to use a moisture meter. These meters can measure water availability at different levels in the container, giving you a better idea of what is going on.
ASK ED: Marijuana Questions
WASHING LAVA
I have just started to try out lava rocks in 8" baskets using ebb and flow tables. I was told to wash the lava rocks before using. I gave them a good rinsing, but it wasn’t good enough. The dye has been washing off, giving everything a red tint (except the plants). I drained and cleaned everything, but still some has remained. Is this dye harmful to the plants, and what is a good way to rinse the lava?
The red stuff that is rinsing off the lava is not dye; it is lava dust. Red is lava’s natural color due to its iron oxide content. Once most of the dust has been rinsed off, its time to use the lava. Don’t worry about small amounts of it in the water. After the lava is used for a short time, the water will drain clear.
6.Automating this unit is not difficult. Place the garden above the reservoir. A tube attached to a submersible pump in the reservoir lifts water into the tray above. The pump is controlled be a short cycle timer and possibly a float valve switch. The tray’s drain is designed to flush slowly into the reservoir. When the pump turns on, water flows into the tray faster than it drains. The recirculating water dissolves dried salts and freshens the water in the medium. When the pump turns off the water drains back into the container from the tray.
7.An overflow drain installed at the maximum water level prevents flooding and other accidents if a timer controls the pump’s off switch rather than a float valve. This is a necessity.
EQUIPMENT REQUIRED FOR AN AUTOMATED EBB AND FLOW SYSTEM
•Tray to hold rockwool or containers
•Rockwool or Planting Containers
•Planting Medium (if using containers) LECA or VermiculitePerlite, or Peat Moss Mix
•Short Term Timer
•Float Valve Switch (Optional)
•Submersible Pump
•Tubing
•Several ebb and flow gardens can be plumbed to a central reservoir using a pump for each garden. The lost water can automatically be replaced from a reserve reservoir.
Ebb and Flow system kits and components are readily available commercially. The ready-made systems are convenient, reliable and have ironed out all the kinks that a home-builder is likely to encounter. Components to make your own system are available at hardware stores and indoor garden centers.
DRIP SYSTEMS
Drip irrigation works by delivering water slowly to the planting medium or soil using an emitter installed at the end of the irrigation tubing. Emitters are manufactured to deliver water at a set rate such as 1 gallon (4 l) per hour. The system consists of a submersible pump that delivers water from a reservoir to a flexible tube that stretches the length of the garden. Spaghetti tubing is connected to the central tubing using connectors that are punched into the main line and fit into the smaller tubing. An emitter on a spike that attaches it to the container or cube is connected to the other end. Each container or rockwool block is serviced by its own emitter. Different sized plants can each get the appropriate amount of water by using drippers with different flow rates or several emitters.
Fertilizer residues can accumulate over time in both hydroponic and soil mediums. General Hydroponics FloraKleen makes a good final flush before harvest. It removes accumulated fertilizer salts as well as relieves plant stress. It can also be used monthly to flush and upkeep fertilizer and soil systems.
First a frame was constructed to hold the tray in place. A table could also have been used. The reservoir was placed in the center of the frame so that water drained directly back into it. The tray was placed in the frame. Notice that the drain has been raised about 1.5” (4 cm). After the water drained, the remaining pool of water was used to keep the LECA moist between irrigations. With a moister medium such as vermiculite-perlite this additional water becomes unnecessary and the drain should be left at tray level.
Plants growing vigorously in the tray.
Drip rings deliver water in a circle pattern around the container rather than in one spot. They are a more efficient way of irrigating and are especially useful with LECA. Almost all hydroponic drip systems recirculate the water and include a reservoir that catches the drain water.
Drip emitters are used in rockwool, coir, vermiculite-perlite, peat moss and LECA.
Both the reservoir and wick system units can be converted into active systems with the addition of a pump, tubing, drip emitters and optional features such as an additional reservoir.
One example is a reservoir system in a 4’ x 4’ (122 x 122 cm) horticultural tray that holds 8" (20 cm) tall containers filled with LECA. The plants do well, but providing a constant stream of water-nutrient solution increases the growth rate.
Small submersible pumps with tubing attached are placed in the reservoir, one for each container. Each tube sends a small steady stream of water to the top of the container and it trickles through the rocks. The roots receive plenty of oxygenated water and the spaces between the rocks provide ample amounts of oxygen.
CONSTRUCTING A DRIP SYSTEM
1.A drip emitter system is easy to make using a sturdy table or by building a wooden frame such as two saw horses. Frames can also be made using steel shelving or PVC pipe. If you are using a frame place a piece of ½” (1.25 cm) thick plywood for use as the top. Arrange a slight slope of 2½% (i.e., 1” in 40”—2.5 cm in 1 m) so the water drains easily. Place a piece of corrugated plastic over the tabletop so the water runs along the troughs to drain. Install a drainage trough along the side of the table or frame. The trough is made using plastic rain gutter. Place a holding tank at the end of the trough to catch the draining water.
2.Place the containers or rockwool on the corrugated plastic.
3.Set up the drip system using a temporary reservoir such as a plastic bucket.
4.First, attach tubing to the submersible pump.
5.Place the pump into the temporary reservoir and install the tubing across the center of the garden.
6.Install the spaghetti tubing. First measure the length of spaghetti line required and cut the piece off the roll. Push the connector into the spaghetti tubing. Push the emitter into the other end of the line. Punch a hole in the main tubing using the tool sold with the drip equipment. Push the connector into the main tube and place the emitter into the rockwool or container. Repeat with each cube or container. More sophisticated systems use pressure regulators and filters. These options are highly recommended. Automated systems continually measure water pH and nutrients and make adjustments as needed. These systems are designed for greenhouses and commercial gardens rather than the small garden. Hobbyists who are computer savvy might wish to check out some articles on designing your own computer controlled pH and nutrient delivery.
Drip: the corrugated plastic grooves guide drain water to the gutters.
7.To determine how large a reservoir is required, run the system with the emitters draining directly onto the plastic. Measure how much water is emitted in one minute. If possible use 100 times that amount. If that is too large a reservoir for one reason or another, use the biggest reservoir you can. The smaller the reservoir, the more maintenance that is required.
8.Place a catchment bucket at the end of the table to hold water that pours from the drainage gutter. Place a sump pump in the catchment bucket. Alternatively, devise a drain system that returns the water directly to the reservoir. The water is transferred back to the reservoir.
9.Place the pump into the reservoir. The system is ready to go.
EQUIPMENT NEEDED FOR DRIP SYSTEM #1
•Table or frame with sturdy
top such as 0.5” (1.25 cm) plywood
•Corrugated plastic (available in home improvement/building supply stores)
•Trough to catch drain water from corrugated plastic made from a rain gutter
•Rockwool or planting containers
•Bucket for use as a temporary reservoir
•Submersible pump used to supply water to the drip emitters
•Spaghetti tubing from pump to garden area
•Drip emitter
•Connectors from main line
•Punch tool
•Reservoir
•Catchment bucket
•Sump pump
•Pressure regulator (optional)
•Filter (optional)
DRIP EMITTER SYSTEM 2 (FOR ROCKWOOL)
1.This is a design for a system that is on a 4’ x 8’ (122 cm x 244 cm) table.
2.Use a table or frame with a sturdy top.
3.Raise one end of the table about three inches using blocks or supports to facilitate drainage.
4.Outline each foot of the table’s four foot width. Position an 8’ (2.4 m) gutter in the middle of each marked foot. Alternatively, use eight 4’(1.2 m) gutters that cut across the table’s width.
5.Fasten the gutters to the table using silicon glue. If that isn’t sturdy enough use metal fasteners and then seal the fastening with silicon glue. Close the upper end of the gutters using caps.
6.Attach a gutter to the table or frame to catch drainage.
7.Place the submersible pump with tube attached into the reservoir and bring the tube up to the garden.
8.Place eight rockwool cubes in each gutter.
9.Measure drip line length and cut the lines.
10.Attach connectors and emitters to each of the 33 spaghetti drip lines, then connect them to the main line.