The toxins in our tap water are removed using a ‘RODI’ system, making it safe to use in your
aquarium. When it comes to water filtration at home, you can choose between a RO or a RO/DI
system. The only difference between a RO and a RO/DI system is that the RO/DI system adds an
additional filtration step called “DI or Deionization,” which reduces the water’s TDS to zero (total
Difference between RO systems(reverse osmosis) and RO/DI system:
The main distinction between the two is the level of water purity obtained, which is subsequently
used for various purposes. RO systems(reverse osmosis) are used to filter water for freshwater aquariums and to
create drinking water. RO/DI systems provide 99.9% pure water for scientific applications and use in
Stages of RODI system explained:
Input The first stage of your RO/DI system is fed with water or tap water. A hose adaptor, which
connects directly to the threads of your tap or pipe, is commonly used to connect to the RODI
system. You can also utilize faucet adaptors to connect to your existing household faucet or the
plumbing beneath your sink. Because hot water damages your RO/DI system, the input water should
always be linked to your cold water line.
The sediment filter, which is a mechanical filter that collects bigger free-floating material or
contaminants, is found in Stage 1. After a period of use, this filter becomes blocked and should be
replaced every 6-8 months or as needed depending on usage. Over time, the filter will fade from
white to a brownish-yellow tone.
The carbon filter in Stages 2 and 3 is made out of granulated carbon and CTO that adsorbs organics as
well as other dissolved pollutants like chlorine and chloramines. With a five-stage system, you’ll have
two carbon cartridges to handle high usage and target chloramines, which may quickly deplete a
This carbon filter wears down with time and should be replaced every 6-8 months, along with the
sediment filter. Replacing the carbon and sediment filters on a regular schedule will improve the life
of your membrane because it will ensure any possible contaminants are removed before the water
enters the next stage which is your RO membrane—the most expensive and critical filter stage of
your RO/DI system.
How does RO membrane work?
Water enters the RO membrane, which is the heart of your filtration system, after passing through
the carbon stage. Water is filtered via many layers of a thin film, which removes the majority of
contaminants such as salts, microorganisms, heavy metals, and other organic impurities (up to 98
percent). A pressure gauge and/or a TDS meter should be used to monitor the RO membrane. In
most cases, depending on consumption, you’ll need to change your RO membrane every 12-24
The RO membrane divides the water into two distinct water lines: the wastewater line and the
product water line. Your flow restrictor, which is a small capillary inside the tubing that restricts
water flow through the membrane, will be found in the wastewater line. The RO membrane requires
a flow restrictor to function effectively. The flush valve kit, which allows you to flush your membrane
free of particles before and after each usage, will be connected to the waste line.
The product water leaves the RO membrane, the produced water is almost pure, but not quite. This is
why it proceeds to the following level, which includes the DI (deionization) cartridge in the final
stage, water travels through positively and negatively charged resins, which remove any remaining
contaminants such as silicate, nitrate, and phosphate. The product water should have a TDS of 0
after leaving the DI cartridge and be ready to use in your aquarium. Dual DI cartridges can be used to
ensure that no contaminates escape the system.
A pressure gauge will be used to check if your RO/DI system is working properly. The pressure gauge
measures the water pressure entering the RO membrane, ensuring that the needed amount of
water pressure (70 to 100 PSI) is delivered to the membrane for best performance. The minimum
working pressure is 30PSI. When your input water pressure begins to diminish, it’s a sign that your
carbon and sediment pre-filters are blocked and need to be replaced.
Below is a short video on how to install a RO membrane.