Seachem Purigen Review

I came across Seachem Purigen in my research for various items people put into their filtration systems.  The reviews over on Amazon and other sites raise this product to near mythical status. Claims of ultra pure water parameters and and water so clear that it appears water is missing and fish are floating on air.  These promises sounded great, and with such almost universal praise in reviews and at such a relatively low cost, I thought I would give it a try in my Fluval Spec V aquarium.

What is Seachem Purigen:

Seachem Purigen is a filter media.  From their own description on the Seachem Website:

“Purigen® is a premium synthetic adsorbent that is unlike any other filtration product. It is not a mixture of ion exchangers or adsorbents, but a unique macro-porous synthetic polymer that removes soluble and insoluble impurities from water at a rate and capacity that exceeds all others by over 500%. Purigen® controls ammonia, nitrites and nitrates by removing nitrogenous organic waste that would otherwise release these harmful compounds. Purigen’s™ impact on trace elements is minimal.”

All of this is a bit of a mouthful, but let’s first look at what it is physically.

Seachem Purigen in a 100ml Bag

Although I’m sure the engineers over at Seachem could come up with a more wordy description, the product is basically very tiny resin spheres that have microscopic roughening on the surface. From the picture above, you can just make out the beaded makeup of this product. It is not a chemical filter media, such as carbon, but a highly effective mechanical filtration media that specializes in removing “nitrogenous” organic waste material.  That is to say, it targets the removal of organic waste that is typically produced by fish and other aquarium inhabitants.

For myself, the natural question that arises about this miracle filter media that so effectively removes waste is this: does it also remove the fertilizer that I am dosing in my low light tank?  Again, straight from their website, they state that the product does not significantly affect trace elements, including those that I am adding for healthy plants.

It seems to me that Purigen offers many of the benefits that activated carbon touts, but it works with your fertilizers and it cost less in the long run.

Buying Options for Seachem Purigen:

Seachem is sold in various volumes: 250ml, 500ml, 1 Liter, and 2 Liter.  Each liter of material is said to treat 4,000 liters of water (1,000 gallons) for up to six months, so you can work backwards from there to decide how much to purchase.  If you go the route of buying it by itself, you need to contain it inside your filtration system.  As a warning, I have read feedback that typical mesh bags like you would use for ceramic ring media typically have openings that are too large and that will let the Purigen leak out.

Seachem sells a solution in their “The Bag” filter media bag.  It is designed for the purpose and will contain Purigen.  It is listed as 5″ (127mm) x 10″ (254mm).

For my use in a nano aquarium, I decided to go with their 100ml option that comes with the purigen already in a small sealed version of “The Bag”.

Packaging for Seachem Purigen

One of the most interesting things about Purigen is that you can ‘regenerate’ or clean the Purigen once it gets loaded with impurities.  As described in their product description:

“Purigen® can also be regenerated. As it adsorbs waste products, Purigen® will change color from a pale blonde to a dark brown, almost black. Once it is exhausted, it can be regenerated with a solution of bleach and water. The bleach will literally “burn off” the organics that have been removed from the tank.”

Seachem Purigen 100ml with Bag:

This is very convenient option that combines 100ml of purigean in a sealed bag, so no need to get the two separately.  It’s cost effective and dead simple for nano aquariums like my Spec V.

According to their instructions, 100ml would be able to clean 400 liters of water (105.6 gallons).  That will do just fine for a 5 gallon nano I think.

The bag measures around 3-1/2″ x 4-1/2″ (89mm x 114mm).  It is flat – only around 1/4″ (6mm) thick; very easy to wedge into your filter, be it hang-on-back or canister.

Length of Seachem Purigen 100ml Bag

Width of Seachem Purigen 100ml Bag

Seachem Purigen Use in a Fluval Spec Aquarium:

There are some challenges in finding the best place to put the 100ml bag of Purigen in the filter box of a Fluval Spec.  I usually run two separate bags of Biomax in the two compartments.  Initially, I decided to keep those two bags of ceramic rings in place and simply place the bag of Purigen on top of the filter block.

Seachem Purigen located at top of Fluval Spec Filter Section

It kind of fits in this spot, although the bag is a bit too wide. I just shoved it in there an it kind of pillows up in the space.  It is not long enough to fill the compartment so some water bypasses on either end.  The other problem with placement here is that this product is not designed to be run dry – it needs to be submerged.  If your water level gets a bit low, the top of this bag will be exposed.

The water wasn’t getting dramatically cleaner with the Purigen just plopped on top and I got the idea from a forum to place the bag in one of the two compartments cut out of the foam block.

Seachem Purigen 100ml Bag in Filter of Fluval Spec Aquarium

You just fold it in half and shove it in place.  Here I have the Purigen bag in the top section and the bag of Biomax ceramic rings in the bottom.  It fits very nicely in this position. Here is a picture showing how it looks from the other side.

Seachem Purigen 100ml Bag in Filter of Fluval Spec Aquarium

These two pictures were taken after a few months of use; note the dark icky-ness that is starting to build up.

The flow in this arrangement is much better resulting in the clarity improvements I was expecting all along. Even so, I feel like the Purigen would perform even better in an arrangement where the water is fully forced through the entirety of a submerged bag.  This is part of the weakness of the stock Fluval Spec filter block – water will always want to take the path of least resistance, which is around the media inside those cutouts.  Those using this filter pouch in a canister filter will probably realize much more efficient cleaning.

Overall Impressions:

So, does it live up to the hype? I’m not sure if it is as great as some reviews made it out to be.  I can indeed tell there is water in the tank – no fish floating on air confusion.  But, clarity is improved with the Purigen in use.  It does work very well and I think I will have Purigen in my Aquariums for a long time.

The cost is very good.  I got my 100 ml bag of purigen on Amazon for about $10.  Considering that you can regenerate it up to 10 times, that makes it quite a deal.  If you regenerate every 4 months, that would be over 3 years of crystal clear water.  I think it is well worth the money and one of the best aquarium products I have purchased.

I have not noticed any issues using Purigen in a planted aquarium, so their claims that it leaves the fertilizers that you are adding along seem to be true.

I can’t yet speak to the regeneration process, but I hope to do that shortly and will offer a separate post detailing how to clean Purigen and if that is worth the effort.

EDIT: I have now cleaned my Seachem Purigen and that writeup is here.

19 thoughts on “Seachem Purigen Review

  1. Hi, I really appreciate all your helpful tips and ideas on improving the Spec V set up. I’ve only had my Spec V for a few week, and stumbled onto you blog look for solutions to several problems I wanted to solve.

    The one significant aftermarket “improvement” I’ve found that you haven’t discussed here is this after-market media filter basket to replace the stock sponge filter I stumbled upon at Amazon:

    I’m playing trial and error now with what to stock the three compartments with (bio-media, purigen, matrix, carbon), but it seems like a really nice upgrade?

    1. I’m aware of this product and have been curious about reviewing it. I’m also considering how to make something similar and then instruct others how to make it themselves. But, that is a future project.

      Let us know how this works for you and what media you decide on.


  2. Hi, I also use purigen in my Spec V. It does a really great job of clearing the water, especially with driftwood tannins, but I didn’t seem to get that “crystal clear” water that everyone was talking about. I started using KoiZyme in my tank to prevent red leg in my african dwarf frog, and I noticed that this made my tank water incredibly clear (after the first few initial doses which turned the water a bit cloudy). Apparently, not only does it add beneficial bacteria and enzymes, but the KoiZyme acts as a water clarifier as well. Unless you were looking at the water line, you wouldn’t even notice there was water in the tank itself! Just something to consider using in conjunction with purigen.

    1. I haven’t heard of that product – thanks for sharing! I don’t really want to add another chemical so I will probably not try, but I love to learn and will check it out.

  3. Ok so purigen workes well. I have it in a fluval u4 filter. Had to cut half of one of the sponges and fit the bag there. Pls dont put it in the middle of filter as it wont work and the filter will overwork to filter the waste. Bag of purigen needs to be a bit loose. And yes it removed driftwood tannin in about 48 hr up to 80%. The water is much clearer now. I would recomand it during cycles.

    1. I don’t know much about wet/dry filters, but I think purigen would work. It needs flow through it (even if it is dripped through) and the purigen media needs to stay wet (not dry out).

    1. You can use it right away. However, on a new tank it won’t be doing much.

  4. I mistakenly placed the Seachem Purigen 100ml sack in my SPEC – V media filter foam block without rinsing it first. The water in my aquarium is now cloudy. Will this dissipate or do I have to perform a water change?

    1. Sorry for my late response and I hope things turned out ok with your Purigen situation. Was it a brand new tank (newly setup aquarium)? I’d say either action would be acceptable, water change or wait it out until your next scheduled water change.

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