The 4 Best Phosphate Reactor – Why It’s Essential for You

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Let’s face it, we all hate cleaning our dirty fish tanks! I’ll admit it!

Fish poop, algae, uneaten and rotting food particles, debris, and bacteria can contaminate the tank water and build up over time.

With enough time, this build-up can both turn your aquarium into a disgusting swamp and make your fish sick, neither of which are things you want to happen in the aquarium hobby. Trust me, it makes your life a whole lot more difficult!

This is why we have pumps and filters, in order to keep on top of the cleaning. But if your current filtration setup isn’t doing the job, you may need to give it a bit of a helping hand with a media reactor or, in other words, a phosphate reactor.

Different types of filter media are used to ensure clean tanks. The filter medium varies depending on the size of the tanks. Larger tanks use larger tank fittings to control flow rates.

Don’t know what that is? Well, don’t panic!

In this article, we will go over exactly what a phosphate reactor is, whether or not you need one, how to choose the best phosphate reactor, and which is the best media currently on the market to fill it with.

It may seem complicated at first. It took me a while to wrap my head around media reactors and what they do, but, hopefully, this article will help provide a hassle-free solution for you and your fish.

Two Little Fishies Phosban 150 Media Reactor

The Two Little Fishes Phosban media reactor boasts some of the best customer satisfaction of any reactor on the market.

With a media height capacity of 5 inches, it can accommodate 7 oz of Phosban, which is enough to filter tanks up to 150 gallons in size.

Phosban is a very effective kind of synthetic ferric oxide hydroxide granule for removing excessive phosphates. This system is especially useful in reef tanks where preventing algae explosions is so important.

The recommended flow rate for this product is 20 – 30 gallons per hour if you’re using Phosban since higher flow rates can erode this fragile type of media.

You can also customize the reactor to house variable amounts of other media such as bio-pellets, carbon, or sand, with which you may be able to increase the flow rate.

Things we like:

  • Simple, robust design from a trusted brand.
  • A proven system to reduce phosphates over long periods of time.
  • Very good value, given the reputation.

Things we don’t:

  • No hoses included.
  • Over-efficiency in removing phosphate can be detrimental to coral growth.

AquaMaxx FR-SE GFO Hang-On Media Reactor

AquaMaxx is a well-known name in the aquarium world, and this is another reactor that has generally received good feedback from the saltwater and specialist aquarium community.

It is quite a tall reactor compared to others, with a height of nearly 14.6 inches and a media capacity of 1 liter (0.26 gallons).

Like the Two Little Fishes reactor, when loaded with GFO (granular ferric oxide) it can handle tanks of up to 150 gallons. With activated carbon, it can manage a 75-gallon tank, and with bio-pellets, a 50-gallon tank.

Despite the good quality of performance of this filter, there have been some concerns about the quality and longevity of components, such as the plastic screws that need to be screwed open and closed every time you access the media.

Things we like:

  • High-quality performance for reducing phosphates in conjunction with GFO media.
  • Tall media chamber for extended water-media contact time.
  • Adaptable – can house different kinds of media.

Things we don’t:

  • Dubious quality of some components.
  • Plastic screws need to be opened and closed each time to access the filter media.

Avvel Aquatics Biopellet and Filter Media Reactor – Fr-30

This unique design from Accel Aquatics uses a built-in ‘flow accelerator’ that enhances water flow so that bio pellet media is kept constantly tumbling, without the need for a super-powerful water pump.

While this design is excellent for bio pellets that need constant disturbance to reduce nitrate levels, it doesn’t work so well for carbon and GFO, which can begin to erode and contaminate the tank water if over-agitated.

With a height of 15.5 inches, the recommended flow rate for this larger reactor is 150-400 GPH. It can even be used in aquariums exceeding 200 gallons.

A small design flaw for North American users is that this model uses metric rather than imperial pipe measurements, meaning you can’t just run down to your hardware store to buy the right hose fittings – you’ll need to find them from a specialist online.

Things we like:

  • Innovative ‘flow accelerator’ allows the reactor to remain effective with smaller water pumps.
  • Enhanced biological filtration reduces excessive nitrates.
  • Suitable for use in very large aquariums.

Things we don’t:

  • Not so good for carbon or GFO media which can break up if tumbled.
  • Metric components can be a hassle to find parts for.

Sera 32155 Prefix Filter Media Reactor

This simple and adaptable media reactor from Sera can be filled with up to 0.4 gallons of various media for the purposes of a media or phosphate reactor.

What’s nice is that you can also use this unit as a pre-filter for your existing aquarium filter system, to combat cloudiness, pollution, or biological filtration issues.

The slight downfall of this model is that some users have reported faulty seals, which can lead to some serious leakage. Thankfully, the company seems quick and obliging to replace them if needed.

Things we like:

  • Adaptable and versatile unit for various functions.
  • Large filter media capacity increases performance.
  • Good customer service.
  • Inexpensive, simple design.

Things we don’t:

  • Leaky seals are a risk you may not want to take!
  • Less high-spec than specialized media reactors.

What Is a Phosphate Reactor?

A media reactor, or, as the title suggests, a phosphate reactor, is an advanced chemical filtration system suitable for use in freshwater and saltwater fish tanks.

They’re generally cylindrical in shape and allow you to add a choice of filter media into their internal chamber before submerging the reactor in the water. The tank’s water is pumped through the cylinder to filter it.

This allows easier flow control because the water pump can be adjusted to use different water channeling. A separate pump can be used when there are dual chambers in the water tank.

They’re great at preventing phosphate levels in the tank from rising, which can hinder the calcification process, something many aquarium creatures rely on to grow.

Phosphate reactors are a staple piece of tank equipment in the hobby, and many aquarium hobbyists and expert fish keepers claim they couldn’t live without them.

So, if you’re looking for a phosphate reactor, you’ll want to pay particular attention to the media you use to fill it. Some brands are much more effective than others, and we personally recommend RowaPhos, due to its unique chemical composition and just how effective it is.

Do I Need a Phosphate Reactor?

Ultimately, it’s up to you, but whether or not you’ll want a phosphate reactor depends on how quickly your tank usually gets dirty, how big it is, what creatures you keep in there, and how well your current filtration system is working.

Without a phosphate reactor, phosphate levels in the water naturally rise over time, as they’re a byproduct of many fish foods. High levels of phosphates may also interfere with the growth of algae in the tank.

The phosphate reactor you use in your aquarium water depends on various reasons, including water flow rate, algae growth, and aquarium reactors.

If they’re not checked, this can lead to phosphate levels building up, preventing calcification. This can be extremely detrimental to organisms that rely on calcification to grow, such as corals, snails, or coralline algae.

So, a phosphate reactor is more than recommended if you have any of these in your tank. In fact, I’d go as far as to say it’s crucial. After all, I wouldn’t want my snails to suffer!

Excellent devices, such as hang-in devices, act as checkers for phosphate levels. These devices help maintain an impressive capacity by enhancing the cleaning capacity of the tanks.

Studies have actually shown that a phosphate level of 0.19 mg/l will inhibit calcification by around 43%, and water changes alone are not enough to keep these levels under control.

Unchecked phosphate levels will soar within just a few months, which can be deadly to your precious pet snails and corals. This is far more possible when there is no flexible inlet in the reef tanks.

To prevent their demise, a phosphate reactor can be a great addition to your tank to keep these levels in check. Aquarium media reactors are attractive options for saltwater aquariums. On the other hand, an acrylic reactor is effective for PVC pipes.

How Does a Phosphate Reactor Work?

The chemical reactions which take place inside the reactor can be rather complicated to understand if you’re not super knowledgeable in science and chemistry. In order to try to keep things simple, let’s visualize the process.

If you don’t even know what one looks like, imagine the phosphate reactor like a long tube or cylinder. This cylinder is then filled with GFO media (hence the alternative name, media reactor), with the ‘GFO’ standing for ‘Granular Ferric Oxide,’ or, in layman’s terms, rust.

There are many different brands of media with which you can fill a phosphate reactor; some are far more effective than others.

The ‘Iron Oxide’ (GFO) is generally a rusty brown in color and is generally ground up to a somewhat smooth, sand-like consistency.

Water is delivered into this cylinder through the top, and it travels down a tube in the center of the reactor. This then descends into a small chamber beneath the media before flowing back upwards through a dispersion plate, up through the GFO media, and back out of the reactor through a second tube.

The water moving through the media can look like a fluid. This is an essential feature. If water was pushed through the media, it would behave similarly to a mechanical filter and soon become clogged with debris.

The chemical process of phosphate removal only happens inside the reactor, on the surface of the media. Therefore, if clogged, the reactor would become much less effective.

What Do You Put in a Phosphate Reactor?

A phosphate reactor is filled with GFO media (Granular Ferric Oxide).

This is essentially crushed-up iron; however, it’s incredibly beneficial for use in aquariums.

When you first buy a phosphate reactor, you may be recommended a brand that is usually sold alongside the reactor or recommended by the pet store you buy it in. Still, there are various options on the market, and some are better quality than others.

Later in this article, we discuss the RowaPhos. This is a man-made media that has been scientifically proven to be the most effective media on the market. So if you’re looking for the best media choice for your phosphate reactor, read on!

Does a Calcium Reactor Raise pH?

best phosphate reactor

Contrary to the popular misconception, calcium reactors generally don’t raise the pH in your tank. In fact, they’re known to typically cause a small drop in the water’s pH levels, if anything.

In most people’s tanks, the buildup of calcium carbonate produced from a calcium reactor may eventually cause the pH within the tank to drop. This could indicate an improper set-up of the reactor, and in order to prevent the pH from dropping beyond what is recommended for your fish, you’ll want to measure the pH of the water regularly.

How often you measure the water will depend on a wide variety of reasons, including the number of gallons per hour, the kinds of tanks, and the flow pattern.

The initial equipment costs can be high because you might want an excellent choice of handy equipment, such as attachment pieces and decent-quality essential components, both individual and external components.

Many people choose to add a pH buffer to their water if it’s not at the appropriate level. However, this should only be a temporary solution. If this is a situation you’re experiencing, you’ll want to take further measures to ensure the pH of your tank is at a suitable and stable level.

Is RowaPhos A Good GFO Medium?

RowaPhos is one of the market’s top five phosphate reactor GFO mediums.

The Berlin Technical University conducted a series of tests on these top five and found that RowaPhos was the most efficient at removing phosphate from a water source, making it not only one of the most popular but also one of the best.

The other media tested could reach only between 30% and 40% of its removal capacity in relation to weight. Not only did RowaPhos have a higher maximum holding capacity, but, also, it was able to remove phosphates at lower concentrations.

The RowaPhos medium is a one-of-a-kind man-made ferric hydroxide material, which has been created specifically for removing phosphates, arsenic, and silicates from both saltwater and freshwater sources.

RowaPhos was originally developed in Germany to treat mains water supplies. Due to its man-made nature, it should not be confused with natural materials used by other brands, as these are generally aluminum-oxide based.

RowaPhos is incredibly different and, as research has shown, far more effective than competing brands due to its patented manufacturing process, which separates it from other iron-based media which have been released as direct competitors to the RowaPhos brand.

Our Top Pick

After checking out some of the best media reactors on the market, we reckon that the Two Little Fishes 150 Media Reactor is rightly one of the most popular out there.

This is a tried and tested piece of kit from a top brand, and has received a lot of praise from the aquarium community over the several years that it’s been available.

While the company advertises use with their own PhosBan media, this versatile reactor can also be used with other types of media like RowaPhos, bio pellets, or carbon.

It also comes at an affordable price, which is very generous considering its reputation.

To check out some more reviews from aquarium owners using the Two Little Fishes 150 Media Reactor, click here:

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