1
pH
When you talk about the
acidity or alkalinity of a
solution, you’re talking
about pH. This is a
measure of the poten-
tial hydrogen ions
and it is expressed
on a logarithmic
scale between 1-14.
Lower numbers are
more acidic and higher
numbers more alkaline.
The pH of a solution
drastically affects a plant’s
ability to uptake nutrients and can
influence whether the growing environment is hospitable for
beneficial bacteria. That’s because the ionic exchange, which
describes the transfer and changing of different compounds
into forms absorbable by the plant, is influenced by pH.
For DWC systems, the ideal pH level is 5.5-5.8. This allows
for effective nutrient uptake, while reducing the risks
of pathogens or disease. A higher pH can provide
a welcoming environment for root problems like
pythium, while too low pH can prevent nutrient
uptake and be harmful to delicate root hairs.
It’s always recommended to use a nutrient
regimen specifically designed for recirculat-
ing water-based systems if growing with DWC,
as the pH and exchange capacity has been
precisely calculated to keep your garden flour-
ishing. Certain nutrients are balanced with a
mixture of compounds that stabilize the pH
of a hydroponic solution while encouraging
rapid uptake of essential minerals.
“Deep water culture is a hydroponic
method of horticultural production
that suspends plants above an
aerated reservoir solution.”
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4
2
EC/TDS/PPM
Once you’ve made up your nutrient-rich
solution and checked its pH, you need to
make sure the concentration of food —
dissolved mineral nutrient compounds —
in the water is suitable for your crops and
their stage of growth. If too much or too little
food is available, it can be harmful for the plant
and cause nutrient burn, lockout certain elements,
or retard plant growth. Electrical conductivity
(EC), total dissolved solids (TDS), and
parts per million (ppm) are all different terms
for the same measurement: the amount
of ionic salts — those dissolved
mineral nutrient compounds —
in an aqueous solution.
Deep water culture systems
generally require a lower
EC than other methods of
hydroponic production
because the plants have
direct access to nutri-
ment compounds without
a structurally support-
ive substrate. We recom-
mend always following feed
charts but err on the lower
side of concentration ratios.
Generally, an EC of 0.8-1.8 is the
ideal range for the complete life cycle
of any heavy fruiting or flowering plant.
Aeration and Waterflow
Plant growth requires dissolved oxygen to allow root hair
development and for use in transpiration. Dissolved oxygen
refers to the level of free, non-compound oxygen (O 2 ) present in
water or other liquids (as the oxygen molecule in water (H 2 O)
is bonded with another element (hydrogen) in a compound, it
does not count toward dissolved oxygen levels).
In commercial hydroponic systems, the solution is usually
aerated using large air-pumps or creating strong waterfall
arrangements where the water surface is broken by a
constant flow of liquid. Some undercurrent hydroponic
designs allow for the aeration of a central reservoir as
well as each individual pot. Water flow constantly moves
aerated liquid around the system, ensuring consistent
nutrient delivery to every plant. Water movement also
influences nutrient uptake, as insufficient flow or stagnant
areas can cause toxicities and deposits of unused nutrient.
Water Temperature
Correct water temperature
is the ultimate key to
successful recirculating
hydroponic production.
The temperature of
the life-giving liquid
solution influences
nutrient uptake,
dissolved oxygen, and
pH. It can be the cause of
happy, healthy, glowing
white roots or dark, smelly,
disease-ridden struggles.
If the water temperature is too
high, the dissolved oxygen is reduced. Lower temperatures
increase dissolved oxygen potential but cause slower plant
growth. The water temperature also determines whether the
liquid is habitable for living organisms. Higher temperatures
with their reduced amounts of dissolved oxygen encourage
anaerobic pathogens to attack delicate root hairs.
Keeping your water temperature optimized is a balancing
act influenced by both external and internal factors (i.e. light,
room temperature, system design, water pumps, air pumps,
crop cycle). The golden range for water temperature is 64-73˚F.
Cultivation facilities utilize water chillers, and sometimes
heaters, to stay within these parameters.
5
Water Control and System Design
Now that you understand the important parameters of your
hydroponic system, you need to keep them in check. Clever
system design is crucial for effective growth throughout
multiple growth cycles. There are many systems out
there that are fantastic for the first few weeks but become
impractical and frustrating after plant mass develops and
the plumbing is put to the test.
Maximum Yield
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