13 replies to this topic

[Lyntanos]

This is the first time I've used Purigen and I just have a few questions for people.

When it says it can be recharged with bleach, will any supermarket bleach (without added fragrances) be suitable?

I'm guessing you'd need to use a pretty decent dechlorinator after using bleach, I've got "Aquarium Science Chlorine Neutralizer" normal use is 1 drop per Litre (5mL per 50L)

Would this product be alright?
How much would I need to use, how long should I leave it to soak for?

[Pescados]

Hi We use purigen in all our tanks and it's a great product.
I use white king regular bleach as per the instructions on the purigen leaflet - then give it a good rinse under running water then into the declorinator - from memory it's one cup of declorinator to one cup of water - (sorry I'm overseas at the mo so can't check omn the packaging.) I leave it there longer than they recommend then rinse again and hang out on the line to let the sun get at it for a day or so. I'm a bit over cautious but I figure it's better to be safe than sorry - hope this helps
Pescados

[Juls]

I've been using Purigen in all my filters for more than a year now,

I'm gonna take a wild guess that either you havn't read the instructions included, or you don't have them.

To recharge, i just use Home brand (any brand basically) plain bleach. (not scented, needs to be pure bleach)

I keep soaking in bleach and turning it over regularily until it's back to new colour again,
I prefer not to use the bleach totally neat or it can be difficult to get it out again.

In order to remove the bleach, you need to use Quite a bit of dechlorinator,

Seachem suggest using there PRIME which is there dechlorinator at a 1:5 water/prime ratio, and soak overnight,
repeat if there is any bleach smell remaining.

The thing is Prime is rated at 5ml of product per 200L of water.

your dechlorinator is only 5ml per 50L, so realistically it's not going to be strong enough
unless you use it neat (not mixed with water), not knowing how exactly the dechlorinator works however
it might not work at all if not mixed with some water.

i've recharged my purigen successfully more than 5 times,
but i have to admit sometimes it's a bit iffy when getting the bleach out and i end up using quite a bit of prime.
either way i wouldn't live without it, and i keep a spare handy so when i do the filter maintainence i just wip out the old, bung in the spare
and there is no rush to recharge the one i took out.

Realistically it takes 2 days to properly and safely recharge your purigen, you have at least 6-12 weeks use before recharging,
so save up and buy a extra satchel ready for your next filter clean.

Juls

[tsunamisurfer]

I have used and recharge my Purigen a couple of times now, equivalent to a 100ml bag.

Like above I use any brand bleach that is in the house, 1:1 bleach:water.

I actually use much less dechlorinator than the above people.

After soaking in bleach solution overnight or until it has re-obtained its original colour, I give the bag a good rinse with water. Then I soak the bag in just water overnight, then rinse again and this time let it soak overnight again , this time with triple the amount of de-chlorinator I would normally use for new water.

The fish and RCS are fine.

I just make sure that there is no bleach smell, which after 48 hours of rinsing and soaking in water easily gets rid of.

I use a 2L ice cream container so not much water is wasted.

The only thing is this is a 72 hour turnaround, which any normal tank can easily live without.

[sydad]

I have used and recharge my Purigen a couple of times now, equivalent to a 100ml bag.

Like above I use any brand bleach that is in the house, 1:1 bleach:water.

I actually use much less dechlorinator than the above people.

After soaking in bleach solution overnight or until it has re-obtained its original colour, I give the bag a good rinse with water. Then I soak the bag in just water overnight, then rinse again and this time let it soak overnight again , this time with triple the amount of de-chlorinator I would normally use for new water.

The fish and RCS are fine.

I just make sure that there is no bleach smell, which after 48 hours of rinsing and soaking in water easily gets rid of.

I use a 2L ice cream container so not much water is wasted.

The only thing is this is a 72 hour turnaround, which any normal tank can easily live without.

A problem with using household bleaches is that many contain unspecified additives. In the case of scenting agents, these are usually noted by the manufacturer, and are evident regardless, but thickening agents are often added, and are not as obvious: neither are detergents. Both of these can cause problems when "regenerating" Purigen. (Thickeners can cause permanent pore blockage in the resin, and so greatly reduce the efficiency of the product.)
Generally speaking, the cheaper the bleach the less likely it is to contain additives, but I consider that it is advisable to use a bleach that is KNOWN to be free of additives, so I use sodium hypochlorite solution made for swimming pool use.
Although apparently more expensive than household bleach, it is considerably more concentrated, and accordingly cheaper in the end. It is of course necessary to dilute it more.

To ensure elimination of chlorine (and the sodium hydroxide present in all bleaches) it is best to rely on THOROUGH rinsing before attempting to use a dechlorinator, and then thoroughly rinsing again after use of the dechlorinator. Such rinsing need not involve the use of large volumes of water, but a reasonable amount is advisable. If it is considered desirable to save water, extended times of soaking in small volumes with several changes is acceptable: your nose can be a good guide.

Syd.

[Blackcats]

Another question - can this product be regenerated indefinitely or does it eventually have to be replaced. How many recharges are possible ?

Cheers

Harry

[sydad]

Another question - can this product be regenerated indefinitely or does it eventually have to be replaced. How many recharges are possible ?

Cheers

Harry

Theoretically, Purigen can be regenerated indefinitely, but in practice it eventually becomes fouled by substances that are not readily removed by the bleach process: these include some fish slime coatings and long-chain, cross-linked humic acids. Such substances can be eluted with more sophisticated procedures, but these are invariably more expensive and more involved than the bleach treatment, so their use becomes uneconomical.
The best guide to the useful life of Purigen (and related products; though most aquarists do not have ready access to these), is the progressive darkening of the resin, accompanied by reduced efficiency: this latter can be tested with very low doses of methylene blue. If the resin is "exhausted", the methylene blue remains in the water for an extended time, whereas with fresh resin it is quickly removed.

Syd.

[jcahow]

According to Seachem responses on their tech forum Purigen loses approximately 10% of its efficency each time it is regenerated.

Another thing to note is that Bleach has a high PH which is why Seachem used to add a third regeneration step (for fresh water use only) to buffer down the Purigen PH to acceptable levels. They have recently removed this fresh water third buffering step (now optional) or at least recommend buffering the Purigen close to the final fresh water tank PH. This came about because their Purigern instructions listed three different Seachem buffers (acid/neutral/alkaline), any of which could be used in the third regeneration buffering step.

It seems that Purigen tends to retain (short term) the PH of the final optional buffering step which is not normally a problem. Purigen is commonly sold in small 100ml filter bags which dose 100g (400l) and some people use them on much smaller aquariums (30g or less) with no problems. One specific individual ran into major problems using Purigen on a 10g fresh water tank after regeneration. Their tank was normally alkaline (high PH) and they used Seachem acid buffer (low PH) for the third regeneration (buffer) step. When they reintroduced the regenerated Purigen back into their system most of the fish died beause the PH was dramatically lowered overnight in their tank (from PH 7.8 to well below PH 6.0). This problem was greatly amplified because of the small tank size and the specific Seachem buffer they chose. The small tank size was 10 times under the recommended Purigen dosage size which greatly amplified the short term acidic buffering the Purigen retained.

Personally I always use a neutral buffering agent when regenerating Purigen and have never noticed any PH changes when reintroducing it back into my fresh water systems which are all considerably larger.

If you are regenerating Purigen you might want to check the PH of the water after the Prime (or dechlorinization) step as that is the PH the Purigen will try to introduce short term into your system (especially for smaller tanks). I have not had to regenerate any Purigen since Seachem made the third regeneration step optional so I am unclear what the PH is normally after the Prime step but before it was buffered in a final step.

I have also found that the polymer in Purigen can clump together over time and needs to be broken up manually before or during regeneration in order for complete regeneration to happen otherwise the bleach cannot penetrate the clumps well.

[sydad]

Interesting post jchow.

I did quite a lot of work, about 15 years ago, on non-ionic polymeric adsorbents: the water-treatment group to which Purigen and Hypersorb belong. (I wonder if Seachem actually manufacture these products themselves, or if they are "rebadged" from one of the large manufacturers. The reason for my doubts is that production of polymeric adsorbents/ion exchangers is a complex process , usually requiring emulsion polymerisation with numerous steps. I can't see a relatively small manufacturer setting up a plant to do this: I could be wrong, but it's not a question one asks of a company selling an item such as this.)

I worked with products from companies such as Rhom&Hass and Permutit, among others. The one thing I observed was that these products' ion exchange/retention functionality was extremely low: typically below 20 micromoles/litre for hydrogen ion. For this reason I consider it unlikely that buffering action by the resin is likely to be the explanation for the disastrous drop in pH described. I would consider it more likely that there has been sufficient buffer retained within the resin to cause the problem: and this could have been averted by more thorough elution of the buffer by extended washing. If I can mange to pursue this theory in the near future, I will attempt to do so.

Seachem's suggestion that a loss of 10% of adsorption efficiency is to be expected would gel fairly reasonably with my own experiences: particularly when using sodium hypochlorite (bleach) solution as oxidiser/regenerant. This figure is easily exceeded however if household bleaches containing unknown additives are used in the process. I find that using pool grade, concentrated bleach, suitably diluted is the best, and cheapest solution.

I have in the past managed to "regenerate" Purigen more than 100 times with minimal loss of functionality by using a more rigorous, and vastly more expensive regime. This involves the use of polar solvents and ethyl alcohol, is time-consuming, and not practical for non-chemists. Almost certainly not a money saver!
The one thing I would avoid is the use of anything other than other than a neutral buffer, and I prefer to avoid this, and rely on prolonged washing of the "regenerated" resin in clean water. At most I would use only a diluted dechlorinator to ensure removal of residual chlorine, but prefer to avoid even this step when time permits.

Syd.

[jcahow]

Interesting information on Purigen, not sure how much rinsing was done during their regeneration process.

Here is a link if you are interested to the thread where the person had trouble with low PH in a small tank after using acid buffered regenerated Purigen:

http://www.aquariuma...ncy-122023.html

As I mentioned the probem has never effected me directly but it did cause Seachem to specficially change their Purigen regeneration instructions:

This is straight from the Seachem Tech forum and is an answer from Seachem (you can learn about their products by reading through their forums)

Re: Purigen recharge process

--------------------------------------------------------------------------------

Thanks for the post. On the revised instructions for regenerating Purigen, it is no longer necessary to soak the media in a buffer solution. The instructions are as follows:

Soak in a 1:1 bleach:water solution for 24 hours in a non-metalic container in a well ventilated area and away from children. Rinse well, then soak for 8 hours with a solution containing 2 tablespoons of ChlorGuard™, Prime®, or equivalent dechlorinator per cup of water. Rinse well.

As long as you rinse the media well after the dechlorination step and there is no sign of residual chlorine/bleach, the Purigen should be ready for use. We are currently working on changing the instructions on the website and any labels printed in the future will have that step omitted.

I hope this helps and let us know if you have any additional questions. Have a good day!

[BengaBoy]

I know this is an old thread but seems like the best Purigen thread here and thought I would add to it.

 

Just tried the regen for the 1st time.

didn't work (water went black tea colour and purigen stayed discoloured)- then discovered the household bleach was past its use by date; bought some new and its use by date wasn't much more than 12 months so check that first.

 

the Seachem products page and faq have different instructions to what was on the bottle I bought

http://www.seachem.c...es/Purigen.html

http://www.seachem.c...Qs/Purigen.html

 

both say:

soak for 8 hours with a solution containing 4 tablespoons of Prime® or 16 grams of Safe® per cup of water. Rinse well. For freshwater use, soak for 4 hours with a solution containing 2 tablespoon of buffer per cup of water (Discus Buffer®, Neutral Regulator®).

 

 

however another part of the faq says:

The regeneration instructions are specific to using regular 8.25% hypochlorite household bleach (non scented, no dyes). From our research, the dilution of 4 tbsp or Prime® or ChlorGuard for each 1 cup of water volume will successfully neutralize the amount of 8.25% bleach used in the 1:1 ratio. The directions on your package may say to use 2 tbsp of Prime®. This was based on what used to be the most commonly sold houshold bleaches which were 6%. This concentration is not sold anymore. By doubling the Prime® dosage, we are accounting for newer 8.25% hypochlorite bleaches while erring heavily on the side of caution. Also, we would not recommend using a splash-less bleach or a 33% more concentrated bleach as these will not be in the proper form or concentration for the regeneration process. We also recommend smelling Purigen after the regeneration process. If there is a chlorine or bleach smell, repeat the process of soaking in Prime®.

 

 

from what I can tell the White King bleach is 4% - 42gm/L - is that right?

 

the instructions on my bottle (250ml, 150gms) don't include the buffering step either. Whereas both the faq and product guide do.

all pretty inconsistent from Seachem - they have had a few years to sort this now?

 

we won't get all pedantic about what is a cup size, or a tablespoon (US, UK...)

[Rovik]

Use granulated pool chlorine Sodium Hypochlorite, It's more powerful on organics trapped by the purigen.

You'll get a better results.

 

 

Also don't waste the prime,

 

Just get yourself some straight sodium thiosulphate to use as a neutralizer

 

http://www.aquariumo...iosulphate-1kg/

 

 

This is the product that is used in a aqueous solution in most water conditioners to neutralize chlorine.

You can Calculate the exact amount stoichiometrically but you need bugger all.  (Heaped Table spoon would be overkill)

 

In wikipedia we trust:

 

 

 

thiosulfate reduces the hypochlorite (active ingredient in bleach) and in so doing becomes oxidized to sulfate. The complete reaction is:

4 NaClO + Na₂S₂O₃ + 2 NaOH → 4 NaCl + 2 Na₂SO₄ + H₂O

 

 

If Sydney is around, he can give you the complete low down....

[sydad]

Use granulated pool chlorine Sodium Hypochlorite, It's more powerful on organics trapped by the purigen.

You'll get a better results.

 

 

Granular sodium hypochlorite does not exist. The product used for pools is calcium hypochlorite, and I would not advocate it's use in regenerating macroreticular resins, since under some circumstances calcium could be precipitated within the resin, with concomitant loss of adsorbent functionality..Sodium hypochlorite is freely available as a liquid for pool use, and this is the best product to use (appropriately diluted) for the regeneration process.

 

Syd.

[BengaBoy]

thanks guys

 

gave the bags(2) a lot of rinsing in a 15 litre bucket and soaked over night.

now have them in the Prime solution for 8 hours.

 

will look at the Ph then.

It was 8.5 before the soak.

 

do you think I should use some Tang buffer for a 4 hour soak?

seems to be optional in the Seachem guidelines?