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Aquarium product reviews / Filter Media

Seachem Purigen – The Best Filter Media?

seachem purigen

Seachem Purigen

Seachem Purigen is a product that I stumbled upon some time ago and have been using ever since. Purigen is a synthetic filter media that removes nitrogenous compounds from your water. This means that these compounds are removed before breaking down into ammonia, nitrite or nitrate.


Rather than me ramble on, here is Seachem’s description of their product direct from their site:

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 other competing products 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. It significantly raises redox. It polishes water to unparalleled clarity. Purigen® darkens progressively as it exhausts, and is easily renewed by treating with bleach. Purigen® is designed for both marine and freshwater use.


Unparalleled clarity?

Seachem Purigen will make your water crystal clear, or it will certainly help. As I’ve been using it for so long, I was struggling to remember how much of a difference it actually made. So for the last couple of months, I haven’t had any Purigen in my filter.

As a person who is affected by ‘aquarium OCD’, I certainly noticed the difference. It isn’t that my aquarium water was dirty, as I keep to a pretty strict routine, but there was a noticeable difference in overall clarity of the water.

Needless to say, there is now a nice big bag of Seachem Purigen in my filter again.

Below is a shot down the length of my 5-foot aquarium in which I use Purigen, as you can see, it’s pretty clear:


seachem purigen filter media




Seachem Purigen is renewable. As it absorbs organic waste, Purigen darkens in colour, until, it turns completely black. Once it has gone black in colour, it is exhausted and can absorb no more. at this point, Seachem provides directions on how to renew it so that it is ready to use again:


Soak in a 1:1 bleach: water solution for 24 hours in a non-metallic container in a well-ventilated area and away from children. Use regular 8.25% hypochlorite household bleach (non-scented, no dyes, do not use a splash-less bleach).

Rinse well, then soak for 8 hours with a solution containing 4 tablespoons of Prime®, or equivalent dechlorinator per cup of water. Rinse well. For freshwater use, soak for 4 hours with a solution containing 2 tablespoons of buffer per cup of water (Discus Buffer®Neutral Regulator®).

Original colour and full activity should now be restored and Purigen® is ready for reuse. Caution: some slime coat products may permanently foul Purigen® and render regeneration difficult. Do not reuse if the odour of bleach/chlorine is detectable. In case of doubt, soak beads in a small quantity of water and test for residual chlorine with a chlorine test kit.


Does this work?

I have tried to regenerate Purigen a few times using this method. But if I’m honest I haven’t had a huge amount of luck. After renewing it in this way I have found on more than one occasion that the Purigen still smelled ‘bleachy’, so I didn’t risk re-using it.

The good news is that Purigen isn’t too expensive, and it takes a while for it to be exhausted if you use enough of it. That means that it works out almost as cheap to simply replace the Purigen when it is used up. More often than not, that’s the option I use.

To give an idea, I use Purigen in a 580-litre aquarium that is well stocked with messy CA cichlids. On average, a 200ml bag of Seachem Purigen will last around 4 months before being exhausted. £20 every 4 months isn’t too bad to keep my water crystal clear.


Best Filter media?

Seachem Purigen is certainly up there with my favourite products for aquarium filtration. It does a great job and can keep your aquarium extra clear and healthy.

Another great use for it is if you have to go away, if you’re leaving your tank for a while then Purigen is an excellent insurance policy. I have had to work away regularly and it can be a struggle to find a tank sitter who is happy to do water changes. Adding Purigen to the filter can help to extend maintenance time.

That means that if you’re going on holiday for 2 weeks and will miss a water change, adding some Purigen to the filter may save your fishy friends. However, please note that I’m not recommending this as a regular practice.


Seachem Purigen really is an amazing product, if you are considering giving it a go, click here. (As an amazon associate I earn from qualifying purchases).


Please note that Seachem Purigen is a back up to your regular filter media and shouldn’t be used as your only filter media. Whilst it absorbs Nitrogenous organic waste, it won’t do as much for waste that has already been broken down into ammonia, nitrite or nitrate. So Purigen is an addition to your filter media, not your main media.

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I am a fish keeping enthusiast with over 20 years experience. I currently keep American Cichlids (CA) which are my favourite fish to keep so far. I started Seriously Fishy as I noticed a large volume of people on various web pages looking for help with Aquarium basics. I created the first Seriously Fishy book to solve the issue in 28 pages, that led to the Seriously Fishy UK fish forum and blog.

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