BASICS
OF FLUSHING
The flushing of any hydroponic system is done as a practical
matter. Any operator of a hydroponic system that does not at
least occasionally perform this measure will ultimately fail
at growing anything due to the buildup of bacteria, algae,
etc., that finds its way into even the most expertly managed
hydroponic systems. Most systems, while they are in use,
need to be flushed at a minimum of every one to two weeks.
Some growers flush their system between crops; others do it
every time or every other time they wish to add nutrients to
their reservoirs. Frequency of flushing will be dictated by the
needs of the system to keep it clean and the preferences of
the individual grower.
In the decision making process of deciding to use agents,
it is important to consider the reasons for using them. Most,
and arguably all (who aren’t seeking the contrary for research
purposes) growers would like to make sure their plants are
integral components of healthy, living systems, thriving in a
clean environment that reduces the incidence of disease pres-
sure or other external stressors of plant health. Make sure to
understand the differences between cleaning versus trying
to eradicate all bacterial or microbial life. The difference
between sanitation and disinfection is the difference between
wiping things down to collect debris and using a product that
acts as a bactericide, viruscide, algaecide, or other antiseptic.
In general, a flush of your hydro system between crops
with some sort of chemical or biological agent should be
viewed as an opportunity to kill anything and everything so
nothing carries over between crops. If, however, you want to
perform that same type of flush when there are still plants in
the system, that approach will likely kill all your plants, but
more on that later.
FLUSHING AGENT OPTIONS
“IN GENERAL,
a flush of your hydro
system between crops
with some sort of
chemical or biological
agent should be viewed
as an opportunity to kill
anything and everything
so nothing carries over
between crops.”
The range of products available to clean out your hydro
system with a flush can be overwhelming. Arriving at a choice
by asking what someone else uses may not help to narrow
down your selection. Visit any message board on the topic
and you will see almost as many different opinions on what to
use and when to do it as there are individual growers. There
are plenty of products and each can work for your situation
depending on your system and budget.
There are many options for flushing your system that you
may already have in your kitchen or bathroom. Some growers
use simple hand or dish soap when they do a flush between
crops. One drop per gallon is a common ratio for these
DIYers. Other common and effective options include bleach
or hydrogen peroxide — more on those below. Your media,
however, may dictate what type of agent would work best for
your scenario. If you use coco or stonewool, you may want to
consider a flushing agent with enzymes to break down any
dead root or other biomass that may have accumulated there.
There are growers who swear by using just water for
flushing. They typically use reverse osmosis (RO) water,
distilled water, deionized water, or any other aqua with a
neutral pH (7.0). In an otherwise clean system, this may be
all that’s required. Remember, though, you cannot see all
the potential contaminants in a system. Just because it looks
clean, doesn’t mean it really is.
Maximum Yield
25