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Seachem Matrix vs. Seachem Purigen: Which is Better at Nitrate Filtration?

If you want to reduce nitrates from the water in your fish tank, you normally do a water change. With that said, Seachem has a few filtration products that will help reduce nitrates. So which is better, Matrix or Purigen? You can find out in this comparison guide.

Quick Summary

Overall, we find that Seachem Matrix is the better of the two when it comes to nitrate filtration. Not only is it more affordable, the product is also a lot easier to clean. Once you established the nitrate-eating beneficial bacteria (which is going to take at least a month), Matrix should reduce nitrates at a faster rate as well.

With that said, Seachem Purigen is also a great product, especially if you don’t want to wait a month for Matrix to start working as intended. When paired with water changes, Purigen will quickly reduce nitrate levels. Not to mention that you also get the added benefit of having crystal clear water.

You can also use the two nitrate reducing products at the same time if you want the advantages of both. If you are interested, you can purchase the products on Amazon with the following links:

What is Seachem Matrix?

According to Seachem, Matrix is a extremely porus biofilter media. Due to the large amounts of pores, the rocks provide a huge surface area (around than approximately 700 m2 per L).

Beneficial aerobic bacteria will be able to grow on the Seachem Matrix. These colonies are responsible for converting ammonia to nitrite and then nitrite to nitrate.

What separates the Matrix from a vast majority of other biological filters is its ability to grow beneficial anaerobic bacteria that will consume nitrates from the water in your tank.

The internal pores of the media will let water pass through but will restrict its flow at the same time. The aerobic bacteria living on the outer surfaces of the same rock will then consume all the oxygen, leaving nothing for the deeper internal pores. With the presence of nitrates and the lack of oxygen, the anaerobic bacteria can then be grown.

What is Seachem Purigen?

According to Seachem, Purigen is a macro-porous synthetic polymer that is designed to remove both soluble and insoluble wastes from the water of your aquarium.

The pores of this mechanical filter will trap the impurities before they decompose into ammonia, which will turn into nitrites and then nitrates.

By removing organic wastes from the tank water, Seachem Purigen will keep the ammonia, nitrite and nitrate levels in check.

Better Value

In terms of pricing, Seachem Matrix provides a much better value when compared to Seachem Purigen. A 250 mL bottle of Matrix is a lot more affordable than a 250 mL bottle of Purigen. You can check out the current prices for the two products on Amazon with the following links:

Both products come in the following package sizes: 100 mL, 250 mL, 500 mL, 1 L, 2 L and 4 L.

Better at Removing Nitrates

In terms of removing nitrates, Matrix is the better of the two products mentioned in this comparison guide. As we stated previously, the extremely porus media is designed to grow and maintain bacteria that will consume nitrates from the water.

Seachem Purigen works more as a preventative measure as it traps decomposing organic matter in the aquarium to significantly slow down the growth of ammonia, nitrite and nitrate concentrations. Purigen does not reduce nitrate levels on its own. So, if you started out with 40 ppm of nitrates, that level will stay the same with Purigen.

Faster at Reducing Nitrates

Although Matrix will help filter out nitrate from your fish tank, it does take at least a month for the nitrate-eating bacteria to establish itself for you to see any significant results.

The fastest way to remove nitrates is by doing a water change. When paired with water changes, Purigen will be much faster at getting rid of nitrates in the short term.

For example, let’s say your water test kit shows that you have 40 ppm of nitrates in your tank water. By doing a 20% water change, you will, theoretically, bring down nitrate levels to 32 ppm. Since the Purigen is filtering out wastes from the tank before they are converted into ammonia, nitrite and then nitrate, the nitrate concentration should stay at 32 ppm until the next water change.

If you are using Matrix for the first time, the 32 ppm will increase by the time you do the next water change due to new organic wastes produce by the fish. So, the 32 ppm of nitrates may go up to 36 ppm before you do another water change.

Of course, once you have the nitrate-consuming bacteria established on the Matrix, you will be able to reduce the nitrate concentration with or without water changes.

(Note: When doing water changes, we recommend doing no more than 25% over a 24 hour period to avoid stressing and potentially sickening your fish. We suggest checking out our safe water changes guide for more details.)

If you are looking for a short term fix to having large amounts of nitrates, then Seachem Purigen is the better of the two products. Over the longer term, however, we feel that the Seachem Matrix will be faster at removing nitrates.

Easier to Clean

In terms of maintenance, the Matrix is a lot easier to clean when compared to its competition. You simply lightly rinse off any visible wastes you see on the biological media every month or so. You should be using used tank water you are planning to throw away during a water change to keep the beneficial bacteria safe (as tap water contains chemicals that could harm them).

To clean Purigen, you fish have to dip a solution of synthetic polymer that is made up of 50% water as well as 50% bleaching solution. The bleach must contain 8.25% sodium hypochlorite. It should also be splash-less, non-scented and contain no dyes.

After leaving it in the mixed solution for 24 hours, you then have to thoroughly rinse the bleach off the Purigen media. You then have to dip Purigen in a dechlorinator (like Seachem’s Prime or Safe) for another 6 hours. You need for 4 tablespoons of Prime or 16 grams of Safe for every cup of water. If you have a freshwater tank, you should also add 2 tablespoons of buffer (Seachem suggest using Discus Buffer or Neutral Regulator).

After all of that, the Purigen will then be completely regenerated.

As you can see, Seachem Matrix is less of a hassle to clean when compared to Purigen.

Better at Making Your Water Look Clean

Purigen does have one major advantage when compared to Matrix in that it is excellent at making your water look clean due to its ability to filter out both soluble and insoluble impurities from the water in your fish tank.

On the other hand, Matrix is purely a biological media. Thus, it won’t make your tank look clean.

Can You Use Both Matrix and Prime at the Same Time?

Of course, you can simply use both at the same time. The only real conflict that you may run into is when you are cycling a new fish tank. In this scenario, we recommend using only Matrix in the beginning so that you can establish a healthy amount of beneficial bacteria. You can take a look at out fishless cycling guide for more details.

You can then add Purigen once you have a fully cycled tank.


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