Skip to Content

The Ultimate Phosguard Vs Purigen Comparison!

Fish are generally considered a very low maintenance pet choice and compared to a lot of other choices they are.

But caring for fish has a lot of aspects that generally are not considered when first buying a fish.

Since it is the habitat they are living in, keeping the water a fish lives in in a healthy condition is of utmost importance and should not be overlooked. 

There are many ways to keep a fish tank and its water clean, and doing a manual clean of the components of a fish tank will be necessary on a regular basis.

But one of the simplest and cheapest ways to keep a fish tank’s water quality high is by using a chemical filter to keep the water healthy. 

The most common type of chemical filter, and the two types we will be looking at today, are resin based chemical filters.

These are usually very small spheres that you measure out based on the amount of water you are working with. 

After this, you put them in a reusable mesh bag and submerge them in a compartment of your fish tank dedicated to filters.

This is just a basic guide on how to use them, and the specifics vary between different brands and types, but generally speaking, this is how this type of filter is used.

Each type of resin base filter has a different chemical composition that makes them better for dealing with different issues.

Some resin based filters are focused on stopping the water from getting murky, while others are focused on limiting the build-up of certain naturally occurring substances that can be dangerous for fish in excess. 

Two of the most commonly used types of resin based fish tank filters are Phosguard and Purigen. The lead manufacturer and distributor for both of these products is Seachem.

This means that while these products are used in similar ways, they have different enough uses and applications to justify Seachem releasing them as separate products.

So let’s go through the unique properties of each of these products and see what makes them unique and which you think will be a better choice for you!

What Is Phosguard?

Phosguard Vs Purigen

PhosGuard is a resin based filter that was designed specifically for aquariums and is made by Seachem.

It is available in multiple sizes, so you can get the one that fits your needs and tank capacity best.

Some sizes come with the mesh bag needed for use and others do not so make sure to check you have everything you need.

PhosGuard is a great filter because it works well at removing ammonia from the water.

Ammonia is an extremely toxic substance for fish, and if left unchecked it can cause serious health problems.

PhosGuard is also effective at removing nitrate, another toxin that can harm fish. 

While PhosGuard does remove some phosphates from the water, it is not as effective at removing phosphates as some other filters.

If you want to remove phosphates from your water then you may need to consider purchasing a phosphate remover or supplementing your existing filter with a phosphate removal product.

PhosGuard also removes chlorine and chloramine from the water. Chlorine is a natural component of tap water, and although it is not harmful to fish, it can make their skin look yellowish. 

Chloramine is a man-made version of chlorine that is often added to tap water to prevent bacteria growth.

While PhosGuard does not remove all traces of chlorine and chloramine from your water, it does reduce the levels to a point where they are no longer harmful to fish.

PhosGuard also removes many organic compounds such as pesticides and herbicides from the water.

Organic compounds are chemicals that are found in nature, and when they enter our bodies they can cause damage.

Pesticides are one of the most common contaminants found in water, and they can be particularly damaging to fish.

The main drawback of using PhosGuard is that it doesn’t remove heavy metals like copper and zinc from the water.

These metals are very important for fish, but they can become poisonous if they get too high in concentration.

This is why it is recommended to add a metal ion chelator to your filtration system to help keep your water safe.

What Is Purigen?

What Is Purigen

Purigen is a resin based filter manufactured by Seachem.

Like Phosguard, it is available in a good variety of sizes, and you should make sure to have a mesh bag for use if you do not own one already.

Purigen is a great filter because of its ability to remove nitrates from the water.

Nitrates are naturally occurring substances that are present in the environment, but they can become dangerous to fish if they build up in the water.

Nitrate levels in the water can increase over time due to human activity, and this can lead to serious health issues for fish.

Like Phosguard, Purigen also removes phosphates from the water. Phosphate is a naturally occurring element that is essential for plants, but it becomes harmful to fish when it builds up in the water.

Phosphates are removed by Purigen via adsorption, which means that they stick to the surface of the resin beads.

When the water passes through these beads, the phosphates attach themselves to the resin and are then flushed away along with the waste.

Purigen has an advantage over Phosguard because it removes more heavy metals from the water. It does so by removing iron and manganese ions from the water.

Iron and manganese are both toxic to fish, and they will accumulate in the body until they reach a certain level at which point they start poisoning the fish.

Purigen is also effective at removing algae. Algae is a type of plant that grows out of control in stagnant or slow-moving waters.

Algae are usually controlled by adding nutrients to the water, but this isn’t always possible. In some cases, it may be necessary to remove the algae before it starts growing.

Purigen works well at removing algae because it contains resins that bind to the algae’s cell walls.

The algae cells are then broken down into smaller pieces, and the waste products are flushed away with the water.

Purigen is designed to work best when used in conjunction with other filters. For example, if you want to remove phosphorus from the water, you should combine it with a carbon filter.

Carbon helps reduce the amount of phosphate that gets released back into the water during flushing.

Some users have also found that using PhosGuard with Purigen after just using Purigen for a while can boost its efficiency and help with what PhosGuard does better.

Purigen also has more of a focus on keeping the water clear than PhosGuard.

While PhosGuard uses activated charcoal to remove phosphorous, Purigen uses resins that can help prevent algae growth.

If you’re looking for something that will help improve clarity without having any negative effects on the water, then Purigen is probably your best bet.

Finally, Purigen has the added bonus of being capable of regeneration.

When the product needs changing because they have gotten dirty over extended filtration time, you can clean Purigen by soaking it in a cleaning solution and then rinsing it off.

This makes it more of an investment as it can be reused. If you plan on using the products together, make sure to keep them in separate mesh bags if you plan to regenerate the Purigen.

Purigen is recommended for aquariums that contain freshwater fish only. If you plan on keeping saltwater fish, you should consider purchasing a different filter instead.


Both filters do their job well, but there are differences between them. Purigen is a good choice for people who want to keep their aquarium clean and free of algae.

It doesn’t have as much of a focus on removing phosphorous as PhosGuard does, but it does perform very well at removing algae.

PhosGuard is a good option for those who want to remove phosphorous from the water. It’s not as efficient at removing algae as Purigen is, but it will help a little in this area.

Purigen is easier to use, regenerates itself, and is generally speaking less expensive than PhosGuard.

If you want all your bases covered try using both, starting with Purigen, then adding Phosguard, just make sure to store them in separate bags for when it comes time to refresh the Purigen.

Frequently Asked Question

How Often Should I Change My Aquarium Filter?

You’ll need to change the filter every 3 months or so depending on how often you feed your fish. You can tell if you need to replace the filter by checking the color of the water.

If it looks murky or brownish, then it’s time to get a new one.

How Often Should I Manually Clean My Aquarium?

It depends on how big your tank is and how many fish you have. The rule of thumb is once per month. If you don’t see any signs of algae growing, then you can keep to this rule.

What Aquarium Plants Are Good At Natural Filtration?

Aquarium plants are great at filtering out impurities like ammonia and nitrates. They also help keep the water temperature stable. A good choice for this is Java Fern.