5 Best Reverse Osmosis(RO/DI)Water Systems for Aquariums

Reverse Osmosis(RO/DI)Water Systems for Aquariums
By Garrison Hickles Updated

Maintaining and keeping a fish tank clean is not an easy job, to say the least. Anyone who owns an aquarium or keeps a hobby of fishkeeping knows that they could use all the help they can get in order to keep the water of the tank clean.

Thankfully, advancements in the scientific arena have enabled aquarium enthusiasts with the ability to process and clean their tank with much ease. All of these have been possible with the introduction of a Reverse Osmosis/De-Ionization water system, which is also known as RO/DI system.  Now, at first, this may sound a bit complicated but its actual functionality is pretty smooth and user-friendly.

Today, we are presenting before you some of the best RO/DI water systems available in the market. But before we do so, let us learn the benefits of a RO/DI water system and the things you need to keep in mind before you buy one.

Benefits of a RO/DI Water System

There are numerous chemical impurities in tap water. You can’t add water straight from your tap to your aquarium since it will automatically lead to the death of your aquatic pets and plants.

Although a standard filter or a chemical treatment is enough for removing sediments and chlorine, the more fine contaminants such as nitrates, cryptosporidium, lead, and arsenic, among others, can only be removed with the help of a RO/DI water system. In fact, depending upon what kind of membrane you are using, a RO/DI system can filter 99% of the contaminants from any given sample of water.

This ensures not only healthier water for your pets but also the creation of an environment that would lead to fewer algae growth.

Things to Keep in Mind before Buying a RO/DI Water System

Before you buy a RO/DI water system for your aquarium, we highly recommend you to research about it and keeping the following points in your mind:

Flow Rate

The flow rate is presented in terms of GPD (Gallons Per Day) and it signifies the maximum amount of water that your RO/DI system can filter from the tap stage to the final purified stage in a span of 24 hours.

Please note that the GPD that is labelled in the packaging states the GPD of the system if it is run at its maximum pressure. But in reality, most systems will only produce 60-80% of the rated GPD.

If you don’t have access to store the purified water, then a higher rated GPD is preferred since you don’t have to wait around for several hours for the water to get purified. A good way of calculating how much GPD you need is to divide the size of your aquarium in gallons by the frequency of days you perform water changes.

If you can connect your RO/DI system with a storage tank, then a lower-rated GPD would work since you can afford to wait around for a couple of hours for the water to get purified since you would already have some purified water in your storage.

Number of Filtration Stages

The number of filtration system that your tap water is run through in order to get purified is also a major factor you need to consider before buying a RO/DI water system. Depending on your need, you can pick anything from a three-stage filtration system to a six-stage filtration system.

We recommend you to go for a four-stage filtration system that includes a de-ionization stage, a reverse osmosis stage alongside a sediment pre-filter and a carbon filter. Many people underestimate the importance of a de-ionization stage, but let us tell you that this stage is crucial for balancing the pH level of your water. It also adds some valuable minerals to the water in order to balance the presence of ions.

In the case of a six-stage filtration system, two additional carbon filters are present for removing volatile organic compounds, chlorine odour, or any cloudiness from the water. 

Reef tanks generally require a six-stage filtration system whereas a saltwater tank can be taken care of through a four-stage filtration system.

Type of Membrane

Many regard the membrane as the most integral part of the filtration system, and rightfully so since it helps remove the solid particles in your tap water.

Usually, Cellulose Tri-Acetate (CTA) is considered the best membranes for tap water since it has low impurity removal rates (88-94%) compared to other RO membranes. However, you need to remember that you should use CTA membranes only for chlorinated water. Else, they can promote the growth of bacteria. Therefore, if you are using a six-stage filtration system, then you must not use a CTA membrane since chlorine is anyways removed in them.

In a six-stage filtration system, you can mainly see Thin Film Composite (TFC) membranes. They can remove up to 94-98% of solid particles from your water. These membranes can get damaged by chlorine and thus require the carbon pre-filter that we see in a six-stage filtration system.

System Certification

We can’t stress enough on the importance of system certification. Before you make your purchase, don’t forget to look for the certification of your RO/DI water system.

Some of the important certifications that you need to look for in your product are that of NSF and FDA (Food and Drug Administration) ones. While the former is a consumer product testing laboratory, the latter is responsible for helping us understand whether the water that is being purified by the RO/DI system is safe enough to be consumable by humans. This, in turn, indicates whether you can fill up the aquarium with it or not.

Therefore, make sure not to neglect this step at any cost.

With all the considerations being sorted, it is now time to look at the five best RO/DI water systems for your aquarium.

Best Reverse Osmosis (RO-DI) Water Systems of 2020

Our selection has been based on our extensive research of market data and experts guidance. Remember, we aren’t ranking them. They have been listed in no particular order.

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

The LiquaGen 5-Stage Reverse Osmosis/Deionization (RO/DI) Aquarium Reef Water Filter System is an extremely affordable and reputed RO/DI water system in the market now. With its five-stage filtration system, it is highly favoured among fishkeeping enthusiasts.

One of the best aspects about this RO/DI water system is that it’s set up is already done. This means that it is ideal for beginners or for those who don’t want to deal with the hassle of an elaborate setup. With a flow rate of 50 GPD, it is suited for small and medium-size fish tanks. In addition, it comes with a one-year guarantee. It’s TFC RO membrane is one of the best in the business, being able to remove 98% of total dissolved solids in your water.

However, we must tell you that it can be used only with city water. Besides, you also need to ensure that the water that you are pouring into it must have less than 350 TDS (Total Dissolved Salts). If you don’t make sure of this parameter, your system will likely malfunction much sooner than you expect. It is also easier to flush the system with the manual flush line.

Its carbon filters are made of coconut carbon and UDF-activated carbon. This ensures that a wider range of impurities is taken care of by it. In order to help you monitor the output water, it also comes with a pressure gauge and a TDS meter. You will also be notified as to when it is time for you to change the filters.

What We Like?

  • Affordable
  • A flow rate of 50 GPD
  • Ideal for beginners
  • Suited for small and medium-sized fish tanks
  • User-friendly set-up

What We Don’t Like?

  • Can only filter water that is below 350 TDS

AquaFX Barracuda RO/DI Aquarium Filter

Next on our list of best RO/DI water system is the AquaFX Barracuda RO/DI Aquarium Filter with an incredible flow rate of 100 GPD. This four-stage filtration system comes with two-micron chlorine guzzler carbon block filter, which has been widely regarded as one of the best filtration methods by experts.

In addition, it also comes with high rejection and high flow membranes and an in-built pressure gauge. It is also ideal for beginners since it is extremely easy to set up.

It does produce a lot of wastewater. So, it is suggested to recirculate the wastewater to your drain or an outside source. It is also a bit expensive than others. Other than these, this RO/DI water system is an absolute must-buy for your fish tank. It also features a garden hose and a flush valve.

What We Like?

  • Reputed brand
  • In-built pressure gauge
  • High rejection and high flow membranes
  • 100 GPD
  • Easy to setup
  • Flush valve
  • Garden hose

What We Don’t Like?

  • Expensive

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

Next up on our list of the best RO/DI aquarium water system is the Koolermax AR-122 6-stage RO+DI Aquarium Reef RO System. For those of you who have a fancy reef aquarium which is very tough to maintain due to the high demands of coral life, we recommend this water system due to its six-stage filtration system.

This mid-range system comes with a flow rate of 80-120 GPD, and the water that ultimately enters the fish tank will be six times purer than the water you initially pour into the system.

In order to take care of your budgetary constraints, this system enables you to upgrade as well as replace each filter cartridge separately. Therefore, you will be able to run this system smoothly without any worry.

Due to its dual DI stage, you can rest assure that you will have 0 TDS in the final water that goes into the aquarium. So, the fact that it doesn’t have a TDS meter doesn’t really matter in that case.

We do think that the absence of a flush valve affects its shelf life, but you can’t get everything in a single system.

What We Like?

  • Six-stage filtration system
  • Multiple installations option
  • Affordable
  • Presence of built-in pressure gauges

What We Don’t Like?

  • Absence of a flush valve

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

The Fountainhead Water Systems RO/DI Aquarium 4-Stage Reef System is another viable option for those who are looking for a RO/DI water system for their fish tanks.

Featuring a four-stage filtration system, it is ideal for hard saltwater tanks. Fountainhead is one of the most trustworthy brands when it comes to home filtration units, and their work in producing this water system for fish tanks is no exception.

Add to that, there’s the bonus of a lifetime guarantee with the manufacturer. It is a no-brainer as to why you should opt for this RO/DI water system.  This provides a strong flow rate of 150 GPD, making it one of the most powerful ones among the contemporary RO/DI water systems. This means that it can be suited for tanks of all sizes.

It doesn’t come with a pressure valve or a TDS meter, although you can easily upgrade it by buying these two items separately.

What We Like?

  • Four-stage filtration system
  • Options for multiple installations
  • Lifetime guarantee
  • Suited for all tank sizes
  • Powerful 150 GPD

What We Don’t Like?

  • Absence of pressure valve
  • Absence of TDS meter

SpectraPure MaxCap RO/DI System

With a four-stage filtration water, the SpectraPure MaxCap RO/DI System finds a spot on our list. It is a bit costly; we won’t deny it, but given its features, it is totally worthy worth it.

It comes with specialized TFC membranes that are designed to eliminate all sort of silicates from the water. In addition, it also features two digital total dissolved solid monitors. This allows you to keep a close watch on the quality of the water.

Featuring a flow rate of 90 GPD, it is sufficient for filling up a storage tank, if you have one.

It also reduces its wastewater in order to produce twice as much waste as purified water. This is in sharp contrast to other RO/DI system, the majority of which produces four times waste as the purified water.

The presence of a flush calve extends the lifespan of the TFC membrane, which is always an added bonus. It also comes with a three-year warranty system.

What We Like?

  • Three-year warranty system
  • Presence of Flush valve
  • 90 GPD
  • Durable
  • Uses 50% less water than most other RO/DI systems

What We Don’t Like?

  • High-budget


Please do not ignore the importance of a good RO/DI water system for the safety of your aquatic pets and plants as well as for the smooth overall functioning of your aquarium. We hope our aforementioned buying guide and our recommendations of these RO/DI water systems will help you in making a wise decision while making your purchase.

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