Seachem Purigen and how to maintain it. I originally heard about the product on a planted tank website (back when I was running, guess what, a planted FW tank) where I was told it was the choice of many as an alternative to GAC.
I originally wrote this article when I was just getting into saltwater tanks, and I still had a planted tank as well as a few freshwater grow-out tanks for livebearer fry. The kiddos loved baby fish! What prompted me to write it was actually when I crashed the pH a 10g fry tank after putting in a freshly recharged 100mL bag. More on this at the end of this article. Note that this occurred after following their directions to the letter with respect to the additional freshwater-use step of soaking in a buffer. Seachem was able to reproduce what I had done exactly, and changed the wording on the box label, but it doesn't seem that this is actually reflected on their current website. The extra steps that I have added are more important for FW systems - essentially, an alternate to the buffer step.
What is Purigen?
In case you are not familiar with Purigen, it is a synthetic polymer resin that has (in the past) been marketed as having the ability to reduce ammonia, nitrite, nitrate, etc. It actually does not (and their FAQ reflects this). It removes/adsorbs dissolved organic matter before it gets consumed by nitrifying bacteria, therefore it can reduce the resulting buildup of Nitrate. It also has a water-polishing quality, and it adsorbs a wide variety of chemicals. However, unlike GAC, it won’t remove nearly the amount of nutrients that plants require (fertilizer supplements).
Regeneration (or "recharging" as I sometimes call it)
Seachem describes the regeneration process on their product page, towards the bottom. I follow about the same procedure, with a few variations. First, you have to know when it's time to regenerate it. This is what a fresh bag of Purigen looks like (100ml bag)
This is what it looks like by the time it needs regeneration. The larger bag on the left is out of a FOWLR tank and is 250 mL, the middle bag is from a reef tank, and the one of the right is from a highly overstocked 10g FW fry tank (years ago...)
When used in SW, I found that it takes on a more brownish and even coloration; while in FW it ends up more salt-and-pepper looking, some beads will turn almost black and some will stay pretty light. I don’t know why this appears to be the case...it’s just an observation. IMO, Purigen is ready to regenerate whenever it has, for the most part, changed color to brown or black.
Use a glass container for the whole process. First, I start by rinsing the product very well in luke-warm tap water. I prefer to use a large flower vase like this one:
If you don't have a flower vase like this, well then...it's probably time that you buy someone flowers for someone, or yourself! They die off in a few days, but you'll make someone happy during that time, and you'll be left with yet another "procured" piece of equipment to add to your reefkeeping supply pile. Dual purpose!
I prefer to empty the contents out of The Bag into the vase but you don’t have to. Since the product sinks in water, open the bag and dump the beads out into the vase, then run the bag under slow-running water to rinse the beads out.
Most of the beads will settle to the bottom within a minute or two
Slowly pour out the water (the key here being slowly) so that the Purigen doesn’t get stirred up. You can’t pour all the water out...so don’t try.
Fill it up again...
Let it settle again...
Pour out the water...repeat this a few times. On the last time, leave a little bit of water
Pour in straight bleach (regular, no fancy ingredients or fragrances) to at least a 50/50 mix. 50/50 is Seachem's recommendation, I have been known to use more.
Give it a good swirl
If necessary, top it off with some water (RODI or tap, either is fine)
The beads will almost instantly turn white (less than a minute)
Let it soak for a full 24 hours. I stir it occasionally, maybe a few times a day.
If you leave the Purigen in The Bag (that's what they call it) or you are using the pre-The Bagged 100ml pouch, it’s a similar procedure. You rinse well in luke-warm tap water
Get a glass vase
Pour in the bleach
Top it off with water
As you can see, I use the handle of a toothbrush to stir up the mix a couple times a day. With the product out of the bag, it’s easy. In the bag, IMO you have to swirl and prod and turn the bags to make sure the entire product is getting some bleach contact
I recommend covering the vase with paper towel, because the surface of the water will develop a skin overnight. Not sure why, and I’m sure it’s fine, I just prefer to cover it.
If you use “The Bag” for other media as well, it can get stained. This doesn’t affect the functionality as far as I can tell, but I also recommend bleaching The Bag to make sure that it remains clean and porous.
After 24 hours or soaking and stirring, pour off the bleachwater and rinse the loose beads (same steps as outlined above for "before" the soaking process). Repeat about 3 or 4 times (at least) and take out the pre-bagged ones and rinse them for about 2-3 minutes each under the faucet (after rinsing in the vase several times). It looks brand new now!
But it’s not ready - you need to neutralize the bleach! Pour off all possible water, then add Prime. It's important to note that you should not use any other dechlorination product other then Prime! Seachem notes this and explains why in the product page FAQ.
Fill to about here
Add a small amount of RODI water
And let that soak for another 24 hours, stirring occasionally.
As you’ll notice below, it looks the same color as the new bag, if not even a little whiter.
For the loose media, pour it back into “The Bag” which isn’t too hard, except for the last few beads. Swirl the vase to suspend the media, and pour it into The Bag; a funnel can help. Some beads will stick to the container, and you’ll have to wash them back down, swirl and quickly pour several times to get them all. Then zip-tie The Bag.
At this point (after thoroughly rinsing) Seachem says it’s ready for use as long as it doesn’t have a bleach-like smell. If in doubt, soak in RODI water for a while and test for chlorine residue.
I prefer to take the next preventative step (next paragraph) to ensure that the product is completely neutral. I do this to ensure that it doesn’t throw off the pH in the tank you put it in.
This is what happened to me back in 2009 before they changed their package directions. There used to be an extra step for FW to soak in Acid Buffer or Discus Buffer (this is actually still on their website, but I'm not sure if it is still on the actual package). I put a 100mL bag in my 10g FW Guppy fry tank HOB filter after regenerating it, the pH dropped from 7.8 to 6.0. I brought it to their attention and they were able to duplicate the process I went through and verified it. They (at that time) changed the label and I got a bunch of free stuff. Yay me! Anyways...I performed this additional process (below) and tested the pH along the way and found out that in a small volume of water (5g) the pH will still drop. Not nearly as much as it did after soaking in Acid/Discus buffer, but it still does – maybe from 9.5 to 8 in an hour in 5g. Probably not noticeable in a 30 or 55 or bigger, but in a 10g a half-point swing in an hour could cause problems. “Rinse well” is completely relative!!!
Anyhoo, I take the Purigen and put it in a 5g bucket and fill it with luke warm tap water (and a little Prime to decholr the tap water), add power head, and let that run for about an hour. Make sure the power head has an intake guard or foam on it. Very little chance of it, but the edges of The Bag could get sucked into the impeller and chew it up. The result is, well, purigen everywhere. Not a loss, just a pain!
Here’s the pH at the start
Here it is at the 1 hour point
At this point (1 hour) if the pH has dropped much more, I would dump out the water, fill again, dechlor, and run the powerhead for another hour. Repeat as many times as you need, but it should be OK after the first cycle through. Keep in mind that this is 450mL of purigen in a 5g bucket and it dropped about 1.5 points. This is enough Purigen for a 450 gallon tank (according to Seachem). You wouldn’t likely notice a change in pH at all in that size system, or even in a 45 gallon system for that matter...but my opinion is, why take that chance? This is a cheap and easy ‘safety’ step.
At this point, it is ready for use in your aquarium for another extended period of time depending on your bio-load and your water quality.
I rinse it well every week or two with luke-warm tap water to make sure it’s free of trapped waste, stays mixed up, and more importantly to make sure The Bag material stays porous. If you use it in a canister or media basket, the coloration will be striped black/white where the water flows through the tray.
The entire regeneration process costs about $20 in materials, including the vase, bucket, bleach, and Prime. The Prime is probably the most expensive part, unless you have to buy the flowers to get the vase; but don't hold me responsible for that extra cost! You should really be buying flowers more often anyways.
Thanks for taking the time to read this! I welcome any comments, suggestions, or corrections.
"Floyd R Turbo"
Turbo's Aquatics, LLC
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How to "Regenerate" Seachem Purigen
Seachem Purigen is a synthetic polymer resin that removes dissolved organic matter. It also has a water-polishing quality, and it adsorbs a wide...