5 Best Reverse Osmosis (Ro-Di) Water Systems

A ‘Reverse Osmosis’ water system, more commonly known as an RO/DI system, is a device that’s designed to work in sync with the existing filter in your aquarium tank. What it does is clean and process your water with the aim to remove any potential pollutants and contaminants that could cause harm to your fish or plants.

In most cases, this is an essential piece of equipment when it comes to keeping tanks with reef displays because even the tiniest form of contaminant could cause a health problem and ultimately cause the destruction of your reef.

In fact, the vast majority of RO/DI systems have been proven to eliminate up to 99% of all impurities thanks to recent technology, but even so, how can you be sure you’re choosing the system that’s right for you and your tank?

Today, we’re going to explore the ins and outs of five of the very best systems out there. We’ll explore each in detail, giving you all the information you need to know in order to choose the one that’s perfect for your setup.

AquaFX Barracuda RO DI Aquarium Filter

AquaFX Barracuda RO/DI Aquarium Filter

To start off our list, we’ve chosen the AquaFX Aquarium Filter and for fantastic reasons. Firstly, although this filter is towards the higher end of the price bracket, it is one of the most featureful, providing you with a complete 4-stage filtration system to help your aquarium stay pristine for longer.

Interestingly, two of these stages comprise of the 2-micron chlorine guzzler carbon block filter, which is renowned for being one of the most effective filtration methods in the aquarium industry.

There’s also a range of other features, such as a built-in pressure gauge and high flow and high rejection membranes, which are musts if you’re serious about maintaining a proper aquarium environment.

This particular system rates at an astonishing 100GPD, making it one of the most powerful, ensuring it’s fully capable of fulfilling all your needs. The system is really easy to set up, and there are numerous saying it’s no hassle to connect up to wherever you want it to go, regardless of what tank you’re using.

In fact, there’s really nothing bad to say about this filtration system, other than the price which might be a bit much for someone starting out, but even if you are, this is a system that will stay working with you for many years to come.

  • Capable of processing at 100GPD
  • A 4-stage filtration system to keep your aquarium water clean
  • Incredibly easy to set up and install
  • Can remove all chlorine from your tank water
  • The price might be too high for some tank owners

SpectraPure MaxCap RODI System

SpectraPure MaxCap Ro/DI System

Next up, we’ve opted for the SpectraPure RO/DI system, which is the most premium option on our recommendation list. Whether you’re a beginner looking for a piece of equipment to scale up with your tanks, or an expert looking for the best solution, this is it.

As ‘premium-quality’ suggests, this is the most expensive item on our list, but it’s also the one that’s going to give you the best experience, and really isn’t that expensive compared with a lot of other RO/DI units.

Easily the most notable feature of this device is the fact it’s a ten-stage filtration system, which makes it the ultimate true power when it comes keeping your aquarium water contaminant-free. It’s also an alkaline-based system, which means your tank water will hold up to 20% more oxygen than regular water!

What you’ll love about this system, in addition to the 90GDP operating capacity, and the ability to remove up to 99% of negative pollutants, including chlorine, fluoride, lead, and bacteria, is the fact you’ll be able to enjoy the outstanding 2:1 waste ratio, meaning you’ll always be using less than 50% water than your typical filtration system.

Furthermore, every aspect of the system has been designed with quality in mind, from durable, anti-rust brackets, easy fitting and removal and automatic shut-off values, all in all, providing you with a flawless and effortless experience that will keep you flowing for years to come.

Again, there is really nothing bad to say about this product, and you really do get what you pay for! If you’re looking for long-lasting quality and the highest level of performance, there’s no reason to look further than this.

  • Cleans 99% of all bacteria and pollutants in your aquarium tank
  • Uses 50% less water than traditional filtration system
  • Incredibly easy to use with really durable parts
  • Processes over 90 gallons of water per day
  • The premium price tag

LiquaGen 5-Stage Reverse Osmosis Deionization RO DI Aquarium Reef Water Filter System

LiquaGen 5-Stage Reverse Osmosis/Deionization RO/DI Aquarium Reef Water Filter System

The LiquaGen filtration system is another fantastic system to choose for your tank, but this time leading the pack in terms of affordability. If you’re looking for an inexpensive option that does the job well and is a nice balance between all buying criteria, this could be what you’re looking for.

This filter system is ideal for beginners since it’s delivered already set up, constructed and ready to go. Once installed onto your tank, it’s capable of processing around 50GPD which is ideal for small to medium-sized aquariums.
It also comes with a 1-year manufacturer’s guarantee!

The only real downside to this is the fact that is can only be used with city water, and you’ll need to check to make sure the TDS (total dissolved solids) doesn’t exceed 350TDS. Otherwise, it’s not going to work properly and will break.

Apart from that, this awesome 5-stage filtration system will perform fantastically at keeping your tank water clean and your fishes and plant life happy, and you’re sure to find what you’re looking for here.

  • Capable of processing up to 50GPD a day
  • Very affordable and suitable for beginners and experts alike
  • Ideal for small-medium sized aquarium tanks
  • Comes pre-assembled for easy installation and mounting
  • Will not work with water over the 350TDS mark
  • Less powerful than other systems on this list

Fountainhead Water Systems RO DI Aquarium 4-Stage Reef System

Fountainhead Water Systems RO/DI Aquarium 4-Stage Reef System

Another super-affordable aquarium filtration comes from Fountainhead Water Systems, another powerful 4-stage filtration system manufactured directly in the US. While this filtration is one of the cheaper options, this one uniquely packs a punch.

This is because it’s capable of processing up to 150GPD, making it one of the most powerful systems on our large, and ensuring it’s ideal for aquarium tanks of all size. What’s more, this model takes the majority of universally-sized cartridges, which means you won’t need to pay out for expensive ones.

You even got a lifetime guarantee with the manufacturer, so you know you can make this single purchase, and you’ll have a filtration system that will last the rest of your life; that’s how sure Fountainhead are with the quality of their products.

With the ability to work with all kinds of housing and pipes (it’s recommended clear, so you can see exactly what’s going on throughout the system), this is a versatile solution you, your fish and plant life are going to love.

  • Comes with a lifetime guarantee
  • Super powerful and can process up to 150GPD a day
  • Suitable for tanks of all sizes
  • An incredibly affordable option
  • None!

Koolermax AR-122 6-Stage RO+DI Aquarium Reef RO System

Koolermax AR-122 6-Stage RO+DI Aquarium Reef RO System

The final filtration system we’re exploring today is the Koolermax AR-122, another incredibly affordable solution that comes with everything you need and more in a simple yet effective reverse osmosis device.

This is a mid-range to powerful system that’s capable of processing between 80 and 120 gallons per day, and filters through six unique stages, meaning your water will be filtered six times from impurities and pollutants for the best end result.

Of course, you’ll be able to replace and upgrade each filter cartridge as you please which keeps everything affordable and running smoothly. There are even built-in pressure gauges you can monitor to make sure you know how each stage is doing and when it will need replacing, ensuring you’re able to optimize your device’s performance. All parts are assembled and manufactured in the USA and are also FDA approved for your health and well-being!

Overall, this is a hugely popular high-quality system, especially regarding the price and there’s really nothing wrong with it, meaning this is a consistent filtration system you can trust!

  • An affordably priced unit with everything you need
  • Manufactured and assembled in the USA
  • Built-in pressure gauges to monitor performance
  • 6-stage filtration system to keep your water clean and pure
  • None!


As you can see, there are plenty of fantastic reverse osmosis and deionization filtration devices out there, all designed to match the level of performance you need, the aquarium fish tank you’re using and all available within the budget you have to spend.

Make sure you’re taking a detailed look into what system you want and the features you need, and you’ll be able to make sure you’re choosing the reverse osmosis RO/DI filtration system that’s right for you.