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GROWERS INFORMATION -
ARTICLE - WATER FILTERS |
Water Filters: The Choices are Crystal Clear
by Richard Gellert
HE PREVIOUS ARTICLE EXPLAINED the importance of using pure
water as a base for a successful feeding program. Starting
with clean water for your nutrient formula ensures explosive
results in all types of gardening and hydroponics. Also
discussed were the various contaminants that can be present in
your water and the damage they can do to your prized crops.
Now that you know purified water is the base you want to start
with for any feeding of your plants, which type of water
filter is the right one for you?
The proper filter for your situation depends on the source water. A
good place to start is having your water tested to determine several
important values that affect water quality. The previous article
mentioned several sources of obtaining your water’s readings, and
your local indoor gardening shop may be of great help. The ppm
(parts per million) of your TDS (total dissolved solids) is going to
be very telling. Any values over 150 ppm and you are merely guessing
at what hides in your water. But ppm is only part of the story. What
this ppm is made up of is the other part.
There are a variety of contaminants that you can read on a ppm pen.
Hardness is usually a large part of the total ppm you’re reading.
Hardness is the amount of dissolved calcium and magnesium in your
water, and too much of these can create all sorts of problems, the
main one being nutrient lockout. Usually measured in grains of
hardness per gallon, GPG, each GPG equals 17.1 ppm of hardness.
Starting with very low values of these minerals is the best way to
ensure proper feeding and healthy plants.
The other part of the ppm reading is sediment, rust, chlorine,
chloramines, iron, sulfur, volatile organic compounds, and, too a
lesser degree, heavy metals and pesticides. These nasty pollutants
should be kept far away from your prized plants and fruits. If you
don’t drink your tap water, then you probably shouldn’t be giving it
to your plants.
Fortunately, many hydroponics shops have choices of water filtration
systems to help you deal with your particular problems. Take a look
at the table below to determine what type of filter may suit your
needs best:
You can see that a reverse osmosis system can remove all of the
contaminants and seems like the best choice, though if you have
extremely hard water (12+ grains per gallon (~4 L) or 200+ ppm
calcium), then a softener is recommended to pre-treat the water
before going into an RO filter. The softener does a great job at
quickly and efficiently removing hardness, making it much easier for
the RO machine to clean the rest of the pollutants.
Softeners exchange calcium and magnesium for sodium chloride (table
salt), which is harmful to plants but easy to remove with reverse
osmosis. Potassium chloride can be substituted for salt and is
tolerated by plants, but it is twice the price of sodium chloride.
The potassium levels end up being a bit high for delicate plants, so
a reverse osmosis system is recommended afterwards for the ultimate
in pure water.
Carbon and sediment filter systems are essentially instant
dechlorinators and dirt removers. You will normally not see a huge
drop in ppm like you will with a reverse osmosis filter. If the ppm
is primarily sediment, chlorine, and organic compounds, then a
reduction in ppm can be seen, but that is not the primary purpose of
these machines. Most dechlorinators have higher flow rates than
typical RO filters and are priced more affordably. They remove 99
per cent of harmful chlorine and 85 per cent+ of chloramines to
ensure that the living microbiology (beneficial bacteria, fungi,
trichoderma, etc.) in your nutrient solution, and in the soil and
root zone, remains healthy and thriving.
If you want to remove not only chlorine and sediment but also
everything else, then a reverse osmosis filter is what you need.
Reverse osmosis technology is the ultimate solution if lowering your
ppm is the primary concern. A good RO machine is capable of removing
95 per cent of everything in your water, producing soft, pure H2O.
The heart of an RO machine is the membrane, which does the majority
of the purifying. Most membranes are designed to last two to four
years, depending on the quality of the source water and frequency of
pre-filter changes. Most reverse osmosis machines can handle a
maximum hardness of seven to 10 grains per gallon and a TDS of 1000
ppm. If your water is much harder than that, either invest in a
softener or be prepared to change membranes more often.
There are several specialty filters available to deal with
particularly nasty situations. Some people on well water experience
high sulfur levels, indicated by a typical “rotten egg” smell and
taste. High levels of iron can also require specific pre-treatment.
An overabundance of either of these can be harmful to plants and
humans, and a water-conditioning expert in your area should be
consulted.
So, don’t be afraid of the unknown pollutants hiding in your water.
Find out what those contaminants are and use the above guide to help
you find a solution. Many hydroponics shops carry a variety of water
filters capable of helping with your water problems. Most of these
shops can be very helpful in determining which is the correct filter
for you and your plants. |
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