FishLore.com's Freshwater Aquarium Book
REVERSE OSMOSIS FILTER FOR AQUARIUM WATER
What is a Reverse Osmosis Water Filter System and should I use it for my aquarium?
Reverse Osmosis and Deionization is a process whereby water is purified as the water gets
pushed through some sort of membrane. The membrane traps the impurities and they can
remove 90% - 99% of the impurities from the water. The type of membrane you use determines
the amount of impurities that the Reverse Osmosis unit will remove.
Our drinking water often includes minerals, heavy metals (mercury, copper), phosphates,
nitrates, pesticides and herbicides (from farming and lawn fertilizers), chlorine and chloramine.
These can all be potentially harmful to your fish. However, most municipalities do a decent job
of eliminating most of these impurities from our drinking water. Water treatment plants add
chlorine and chloramine to the water to kill any harmful bacteria or other "bad stuff".
One side effect from using a Reverse Osmosis unit is that they will remove some of the "good
stuff" along with the "bad stuff". Because of this you will need to add the "good stuff" (minerals
and other essential elements) back into the water before using it in your aquarium. There are
products on the market called RO Conditioners which are made specifically for this process. R/O
Right is one product that contains the essential minerals and other elements that your fish
need. It should be noted that these are only used for freshwater tanks because saltwater mixes
already contain the essential elements you need.
Is a Reverse Osmosis Water Filter Really Necessary?
If you are planning on keeping a saltwater reef tank with various corals and anemones or a
live in an area where you can only get well water or your water source is suspect, it may also be
a good investment. It really depends on the water coming out of your tap. Some water
treatment centers will send out annual reports of the water quality in your area. If they don't,
there are places that you can send your water off to be tested, all for a fee of course.
For most hobbyists these Reverse Osmosis units probably are not all that necessary. Many
tropical fish hobbyists have been keeping fish successfully for years without using a Reverse
Osmosis Unit. If you're a reef tank keeper though you will probably need to invest in one. RO
units are usually fairly expensive and you probably don't need one if you have decent water
quality. Research your tap water to determine the amount of impurities your water contains
and then make an educated decision on whether or not you really need to purchase one of
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