The Unsorted BBS Collection/thegreatunsorted.tar/thegreatunsorted/texts/txtfiles_misc/pot9

Text File | 1991-04-06 | 14KB | 234 lines

Viewed from Centre of Eternity 615.552.5747


                 -+- The Merry Pranksters from Menlo Park -+-
                               10.1990.01.01.09

                  Marijuana Grower's Handbook - part 9 of 33
                               by pH Imbalance
                             "Hydroponic Systems"

                                     from

                         Marijuana Grower's Handbook
                         [Indoor/Greenhouse Edition]
                                 Ed Rosenthal


   Most hydroponic systems fall into one of two broad categories: passive or
active.  Passive systems such as reservoir or wick setups depend on the
molecular action inherent in the wick or medium to make water available to
the plant.  Active systems which include the flood, recirculating drop and
aerated water systems, use a pump to send nourishment to the plants.
   Most commercially made "hobby" hydroponic systems designed for general
use are shallow and wide, so that an intensive garden with a variety of
plants can be grown.  But most marijuana growers prefer to grow each plant
in an individual container.

                          PASSIVE HYDROPONIC SYSTEMS

                               The Wick System

   The wick system is inexpensive, easy to set up and easy to maintain.  The
principle behind this type of passive system is that a length of 3/8 to 5/8
inch thick braided nylon rope, used as a wick, will draw water up to the
medium and keep it moist.  The container, which can be an ordinary nursery
pot, holds a rooting medium and has wicks runing along the bottom, drooping
through the holes at the bottom, reaching down into a reservoir.  Keeping
the holes in the container small makes it difficult for roots to pentrate to
the reservoir.  The amount of water delivered to the medium can be increased
by increasing the number, length, or diameter of the wicks in contact with
the medium.
   A 1 gallon container needs only a single wick, a three gallon container
should have two wicks, a five gallon container, three wicks.  The wick
system is self regulating; the amount of water delivered depnds on the
amount lost through evaporation or transpiration.
   Each medium has a maximum saturation level.  Beyond that point, an
increase in the number of wicks will not increase the moisture level.  A
1-1-1 combination of vermiculite, perlite, and styrofoam is a convenient
medium because the components are lightweight and readily available.  Some
commercial units are supplied with coarse vermiculite.  To increase weight
so that the plant will not tip the container over when it gets large, some
of the perlite in the recipe can be replaced with sand.  The bottom inch or
two of the container should be filled only with vermiculite, which is very
absorbent, so that the wicks have a good medium for moisture transfer.
   Wick systems are easy to construct.  The wick should extend 5 inches or
more down from the container.  Two bricks, blocks of wood, or styrofoam are
placed on the bottom of a deep tray (a plastic tray or oil drip pan will do
fine.)  Then the container is placed on the blocks so that the wicks are
touching the bottom of the tray.  The tray is filled with a nutrient/water
solution.  Water is replaced in the tray as it evaporates or is absorbed by
the medium through the wick.
   A variation of this system can be constructed using an additional outer
container rather than a tray.  With this method less water is lost due to
evaporation.
   To make sure that the containers git together and come apart easily,
bricks or wood blocks are placed in the bottom of the outer container.  The
container is filled with the nutrient/water solution until the water comes
to just below the bottom of the inner container.
   Automating this system is simple to do.  Each of the tray or bottom
containers is connected by tubing to a bucket containing a float valve such
as found in toilets.  The valve is adjusted so that it shuts off when the
water reaches a height about 1/2 inch below the bottom of the growing
containers.  The bucket with the float valve is connected to a large
reservoir such as a plastic garbage can or 55 gallon drum.  Holes can be
drilled in the containers to accomodate the tubing required, or the tubes
can be inserted from the top of the containers or trays.  The tubes should
be secured or weighted down so that they do not slip out and cause floods.
   The automated wick system works as a siphon.  To get it started, the
valve container is primed and raised above the level of the individual
trays.  Water flows from the valve to the plant trays as a result of
gravity.  Once the containers have filled and displaced air from the tubes,
the water is automatically siphoned and the valve container can be lowers.
Each container receives water as it needs it.
   A simpler system can be devised by using a plastic kiddie pool and some
4x4's or a woodem pallet.  Wood is placed in the pool so that the pots sit
firmly on the board; the pool is then filled with water up to the bottom of
the pots.  The wicks move the water to the pots.
   Wick systems and automated wick systems are available from several
manufacturers.  Because they require no moving parts, they are generally
reliable although much more expensive than homemande ones, which are very
simple to make.
   Wick system units can be filled with any of the mixes found in Chart
7-1-A.

                             The Reservoir System

   The reservoir system is even less complex than the wick system.  For this
setup all a grower needs to do is fill the bottom 2 or 3 inches of a 12 inch
deep container with a coarse, porous, inert medium such as lava, ceramic
beads or chopped unglazed pottery.  The remaining portion is filled with one
of the mixes containing styrofoam.  The container is placed in a tray, and
sits directly in a nutrient-water solution 2-3 inches deep.  The system is
automated by placing the containers in a trough or large tray.  Kiddie pools
can also be used.  The water is not replaced until the holding tray dies.
   Passive systems should be watered from the top down once a month so that
any buildup of nutrient salts caused by evaporation gets washed back to the
bottom.

                          ACTIVE HYDROPONIC SYSTEMS

   Active systems move the water using mechanical devices in order to
deliver it to the plants.  There are many variations on active systems but
most of them fall into one of three categories:  flood systems, drip
systems, or nutrient film systems.

                               The Flood System

   The flood system is the type of unit that most people think of when
hydroponics is mentioned.  The system usually has a reservoir which
periodically empties to flood the container or tub holding the medium.  The
medium holds enough moisture between irrigations to meet the needs of the
plant.  Older commercial greenhouses using this method often held long
troughs or beds of gravel.  Today, flood systems are designed using
individual containers.  Each container is attached to the reservoir using
tubing.
   A simple flood system can be constructed using a container with a tube
attached at the bottom of a plastic container [pH: that which the plant
is placed in] and a jug.  The tube should reach down to the jug, which
should be placed below the bottom of the growing container.  To water, the
tube is held above the container so that it doesn't drop.  The water is
poured from the jug into the container.  Next, the tube is placed in the jug
and put back into position, below the growing container.  The water will
drain back into the jug.  Of course, not as much will drain back in as was
poured out.  Some of the water was retained in the growing unit.
   Automating this unit is not difficult.  A two-holed stopper is placed in
the jug.  A tube from the growing unit should reach the bottom of the
reservoir container.  Another tube should be attached to the other stopper
hole and then to a small aquarium-type air pump which is regulated by a
timer.  When the pump turns on, it pushes air into the jug, forcing the
water into the container.  When the pump goes off, the water is forced back
into the jug by gravity.  Several growing units can be hooked up to a large
central reservoir and pump to make a large system.  The water loss can
automatically be replaced using a float valve, similar to the ones used to
regulate water in a toilet.  Some growers place a second tube near the top
of the container which they use as an overflow drain.
   Another system uses a reservoir above the growing container level.  A
water timing valve or solenoid valve keeps the water in the reservoir most
of the time.  When the valve opens, the water fills the growing containers
as well as a central chamber which are both at the same height.  The growing
chambers and the central chamber are attached to each other.  The water
level is regulated by a float valve and a sump pump.  When the water level
reaches a certain height, near the top of the pots, the sump pump
automatically turns on and the water is pumped back up to the reservoir.
   One grower used a kiddie pool, timer valve, flower pots, a raised
reservoir and a sump pump.  He placed the containers in the kiddie pool
along with the sump pump and a float valve.  When the timer valve opened,
the water rushed from the tank to the kiddie pool, flooding the containers.
The pump turned on when the water was two inches from the top of the
containers and emptied the pool.  Only when the valve reopened did the
plants receive more water.
   With this system, growers have a choice of mediums, including sand,
gravel, lava, foam or chopped-up rubber.  Vermiculite, perlite, and
styrofoam are too light to use.  The styrofoam and perlite float, and the
vermiculite becomes too soggy.
   The plants' water needs to increase during the lighted part of the daily
cycle, so the best time to water is as the light cycle begins.  If the
medium does not hold enough moisture between waterings, the frequency of
waterings is increased.
   There are a number of companies which manufacture flood systems.  Most of
the commercially made ones work well, but they tend to be on the expensive
side.  They are convenient, though.

                               The Drip System

   Years ago, the most sophisticated commercial greenhouses used drip
emitter systems which were considered exotic and sophisticated engineering
feats.  These days,  gardeners can go to any well-equipped nursery and find
all of the materials necessary to design and build the most sophisticated
drop systems.  These units consist of tubing and emitters which regulate the
amount of water delivered to each individual container.  Several types of
systems can be designed using these devices.
   The easiest system to make is a non-return drain unit.  The plants are
watered periodically using a diluted nutrient solution.  Excess water drains
from the containers and out of the system.  This system is only practical
when there is a drain in the growing area.  If each container has a growing
tray to catch excess water and the water control valve is adjusted closely,
any excess water can be held in the tray and eventually used by the plant or
evaporated.  Once a gardener gets the hang of it, matching the amount of
water delivered to the amount needed is easy to do.
   One grower developed a drip emitter system which re-uses water by
building a wooden frame using 2x4's and covering it with corrugated plastic
sheeting.  She designed it so that there was a slight slope.  The containers
were placed on the corrugated plastic, so the water drained along the
corrugations into a rain drainage trough, which drained into a 2 or 3 gallon
holding tank.  The water was pumped from the holding taink back to the
reservoir.  The water was released from the reservoir using a timer valve.

                                Aerated Water

   The aerated water system is probably the most complex of the hydroponic
systems because it allows for the least margin of error.  It should only be
used by growers with previous hydroponic experience.  The idea of the system
is that the plant can grow in water as long as the roots receive adequate
amounts of oxygen.  To provide the oxygen, an air pump is used to oxygenate
the water through bubbling and also by increasing the circulation of the
water so that there is more contact with air.  The plants can be grown in
individual containers, each with its own bubbler or in a single flooded unit
in which containers are placed.  One grower used a vinyl covered tank he
constructed.  He placed individual containers that he made into the tank.
His containers were made of heavy-duty nylon mesh used by beermakers for
soaking hops.  This did not prevent water from circulating around the roots.
   Aerated water systems are easy to build.  A small aquarium air pump
supplies all the water that is required.  An aerator should be connected to
the end and a clear channel made in the container for the air.  The air
channel allows the air to circulate and not disturb the roots.  Gravel,
lava, or ceramic is used.

                           Nutrient Film Technique

   The nutrient film technique is so named because the system creates a film
of water that is constantly moving around the roots.  This technique is used
in many commercial greenhouses to cultivate fast growing vegetables such as
lettuce without any medium.  The plants are supported by collars which hold
them in place.  This method is unfeasible for marijuana growers.  However,
it can be modified a bit to create an easy-to-care-for garden.  Nursery
suppliers sell water mats, which disperse water from a soaker hose to a
nylon mat.  The plants grow in the bottomless containers which sit on the
mat.  The medium absorbs water directly from the mat.  In order to hold the
medium in place, it is placed in a nylon net bag in the container.