I have been using Seachem Purigen in the filter section of my Fluval Spec V aquarium for a few months now. I recently pulled up the filter material and the Purigen has now turned a nice, dark brown patina. Their instructions have the following to say about when to clean: “Exhaustion is indicated by a pronounced discoloration of the beads to dark brown or black.” While not yet black, I couldn’t help myself and decided to have a go at cleaning it.
Being able to clean (regenerate, or recharge) this media and put it back into use is a significant positive that I discussed in my Seachem Purigen Review. Their literature states that it can be regenerated up to 10 times. Some people are a bit uneasy about cleaning it as it involves some methodology and materials that could be harmful, namely bleach.
I will rehash Seachem’s exact instructions here, and then I will describe in my own words how to clean your Purigen. From their website: [Seachem has updated portions since this article was first published, and those changes are now included below – I have indicated changes with bold text]
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 color 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 odor of bleach/chlorine is detectable. In case of doubt, soak beads in small quantity of water and test for residual chlorine with a chlorine test kit.”
One notable change Seachem has added over the years is the recommendation to final soak in a buffer for 4 hours if the Purigen is being used in a freshwater tank. I have never performed this extra step, and I have not experienced any adverse effects. My step-by-step instructions below forego the buffer soak (as that is what I’ve had success with), but do proceed with caution and consider complying with their recommendation as a best practice.
Another change is the dechlorinator soak is now a ratio of 4 tablespoons of Prime (2 tablespoons used to be their recommendation) per 1 cup of water.
Supplies Needed to Regenerate Seachem Purigen:
- Aquarium Safe Tupperware Container. Preferably, one that has a footprint that will allow your Seachem bag to lay flat. By aquarium safe, I mean one set aside for aquarium use only that has not been washed with soap. Don’t use a metal container, as the bleach can corrode/react with it.
- Bleach. I choose to use Clorox brand as we have it, and it was mentioned (previously) on Seachem’s website that is what they use. (I have additional comments on the bleach brand and type later on.)
- Seachem Prime Dechlorinator
- Tap Water
- Your Dirty, Nasty Purigen
Step One: Remove your bag of Purigen from the filter. Rinse it under gentle tap water to remove major sediment. Put the Purigen bag into your Tupperware.
Step Two: Measure out the bleach and tap water into your Tupperware in equal parts (to make a 1:1 ratio mix). I wanted to give my Purigen a little elbow room, so I put 1-1/2 cups [350 ml] of water and 1-1/2 cups of Clorox bleach.
Step Three: Let this sit for 24 hours. Every once in a while, I swished the bowl around to mix up the contents, trying to get all the contents inside the bag exposed to the bleach. The smell of this process can be foul – at the end of 24 hours, it had a bit of a dead fish smell. I kept the bowl out in the garage. I would suggest somewhere outside your home. If you’re in an apartment, maybe in the bathroom with the vent fan turned on. At the end of 24 hours, the water was significantly tinted with junk that had been pulled out of the Purigen. Looking good!
Step Four – Rinse the Purigen: At this point, you have a product that has released much of the contaminates stuck to the surface, but it is swimming in said junk and coated in bleach, neither of which you want back in your aquarium. I spent a solid 5 minutes rinsing the Purigen bag under running, cold tap water. Flip the bag over and over to try and get all the pellets exposed to running water.
Step Five – Prime Soak: Rinse out your Tupperware container. Fill with 1 cup [237 ml) of tap water and 4 tablespoons [59 ml] of Seachem Prime. Let that soak for 8 hours. If you are cleaning a larger bag, keep the ratio the same but increase the water to fully submerge the Purigen.
Step Six: Rinse the Purigen again under tap water. That is what the instructions said to do, but then you have chlorinated tap water in your Purigen. This might be overkill, but . . .
Step Seven: Rinse Tupperware, fill 1/2 to 3/4 with tap water, put Purigen bag in, and add two drops of Seachem Prime to remove chlorine. Let that sit for a few minutes. For marine aquarium use, I substitute RODI water for tap water in this step and would probably forgo the Prime water conditioner. Tap water would probably work OK, but I have a hard time finishing with tap water when it’s for a saltwater tank.
Step Eight: Put Purigen back into your aquarium’s filter media.
My 100ml bag of Purigen didn’t get as snow-white as I expected from their description, but it was much cleaner after the whole process.
After adding it back to the aquarium, I had no trouble with my fish or shrimp. It’s not too much hassle, and having it back to nearly its original state is very nice.
If I did this often and relied on the product to be ready at all times, I would consider having two bags with one as a backup to rotate in while I clean the other. When you store the product, make sure to keep it wet; add a splash of water into a ziploc bag and seal it all up.
Update – Results for Saltwater Aquarium Use:
We now have a nano saltwater tank up and running, and I have had the opportunity to regenerate several 100 ml bags of Purigen in rotation for this tank.
The process is the same for Saltwater and freshwater (understanding that I do not do the buffer soak as Seachem recommends for freshwater use). The only difference is one that I mention in the instructions of this article – for saltwater, I give a final rinse and soak in RODI water (as opposed to a final rinse in dechlorinated tap water).
It has worked great. Nothing has died. There are no adverse effects to fish, snails, corals, or anything else we observe in this marine system. I had some trepidation using this process for a more sensitive saltwater system, but it has worked fine.
Having said that, don’t skip steps. Make sure it is thoroughly rinsed with no traces of chlorine left in the Purigen. If you question any part of the regeneration process, it’s best to throw the media out and replace it with new. In the grand scheme of things (considering the high cost of even a simple nano reef setup), it’s not worth risking a tank full of coral and fish over a $12 bag of Purigen.
I know many reefers will not regenerate Purigen – they simply throw it out and replace with new. This is the safest option and is a decision I understand and can respect.
Final Word on Bleach Type:
This past regeneration cycle for our Marine Purigen bags, I looked to see what type of bleach I used. I noticed the phrase ‘splashless’ on the bottle. A closer look revealed only 1.5% of the active ingredient sodium hypochlorite. The regen process still worked ok, but it’s best to stick with Seachem’s recommendation of around 8.25% sodium hypochlorite. Having said that, almost all bleach manufacturers have lowered this to about 6% hypochlorite.
In summary, avoid bleach that uses the phrase “Splashless”, check for around 6-8% sodium hypochlorite, and check the description and ingredients to verify there are no additives (fragrances).