question regarding seachem purigen

[hebi]

hi all, i bought a bottle of seachem purigen today and placed it in a filter bag( although still got some bits drop out). just a few hours later, i noticed some of the beads turned slightly brown. could that be the cause of it absorbing the tannins which cause my 1ft tank water to become yellowish and is it suppose to happen so fast?my tank water still yellowish though from the dw.

also, im using a hang-on filter from ista and before im using purigen, i just place few pieces of filter wool into it. with purigen, can i just completely remove the filter wool but will that affect the growth of beneficial bacteria? if so, how much of the 250ml bottle of purigen should i use for my 1ft tank? the instruction on the bottle not very clear.

last but not least, is it normal for some of the beads to drop out of the filter bag because i cant find any fine mesh filter bag, only managed to get one which looks fine to be at polyart. any other suggestions for the use of filter bags like seachem filter bag?

thanks for advice.

edit: today i saw a bag of floating plant at C328 selling at $2 for a pretty huge packet, but i am not sure what is it and didnt buy it cause i have read about them becoming weeds and cant get rid of them. if im not wrong, the leaves are very small, 0.5cm and has a heart shape. anyone can id them?

[|squee|]

Here's a reference to Purigen for the uninformed: http://www.seachem.com/products/prod...s/Purigen.html

According to the text, Purigen's beads darken as they absorb the stuff in the water. So no cause for concern. Faster absorbing power = good right?

I don't recommend removing the filter wool in favour of Purigen. There's always the need for BB.

Buy some pantyhose from NTUC and use that as your filter bag. It's about as fine as it can get.

For plant ID... pictures please!

[hebi]

oh ok. then do i need to wash the pantyhose thoroughly? cause the brown colour looks dirty haha. and one thing im not sure about the purigen is how many times can it be 'regenerated' before one have to change a new batch? would be great if people who have used them before can share your experience here regarding the plant, i think its duckweed after searching the internet for pics, but nvm i wont be getting it.

O/T: this afternoon, i saw one of my female cherry shrimp swim near the surface below the hang-on filter and slowly climb up the glass surface above the water! its as though its looking for something there, then it slowly crawl down and went to the moss. just something i want to share

[|squee|]

Just give it a good wash will do. A new one is dirt cheap. All the info about Purigen could be found on the Seachem website I believe.

That's normal behaviour for shrimp

[zenscape]

I remember I regenerated purigen afew years ago by following their instructions and my whole tank of 4ft turned yellow overnight. But the first round was good. Thereafter, i threw it away.

[hebi]

I remember I regenerated purigen afew years ago by following their instructions and my whole tank of 4ft turned yellow overnight. But the first round was good. Thereafter, i threw it away.

really?! how come? why would it become yellow since it can absorb the stuff? they will release it too?

[zenscape]

I believe purigen shares the same properties, characteristic and function of activated carbon and zeolite.

Activated carbon is the most commonly used material to purify drinking water. It is an adsorbent, which means it attracts particles and substance in water onto the surface of the activated carbon either by physical and chemical reaction. The reason why we place activated carbon in filter is to pass the water through it and the carbon will then 'collect' the impurities and pass out clear water.

Active carbon is effective because of its large surface area from its pores. Imagine a moon surface. But a large surface area will soon be too occupied by the particles that attracted on its surface. Thats why activated carbon is for temporary used after which it is considered spent and has to be replaced. Otherwise, impurities and particles will leach and return to the tank and becoming more toxic due to its large concentration.

IMHO, the above applies to purigen.

Back to your question. Yes, purigen, activated carbon, zeolite, etc will release impurites back to your tank if you use them for too long without replacement.

I guess the reason why i failed my previous regeneration of purigen was because the particles on purigen could not be effectively lifted. I was too relunctant to use more bleach than recommended to regenerate. The colour of my tank water was the same as the 'spent' purigen.

[Quixotic]

But a large surface area will soon be too occupied by the particles that attracted on its surface. Thats why activated carbon is for temporary used after which it is considered spent and has to be replaced. Otherwise, impurities and particles will leach and return to the tank and becoming more toxic due to its large concentration.

Maurice, with all due respect, I don't think the leaching part is completely and convincingly proven.

An earlier discussion thread on Activated Carbon.
http://www.aquaticquotient.com/forum...30&postcount=6

To summarise, there are many different grades (different specifications) of AC and they are produced via differrent process. One of the production process is described here, http://en.wikipedia.org/wiki/Activated_carbon:

Chemical activation: Impregnation with chemicals such as acids like phosphoric acid or bases like potassium hydroxide, sodium hydroxide or salts like zinc chloride, followed by carbonization at temperatures in the range 450-900 °C. It is believed that the carbonization / activation step proceeds simultaneously with the chemical activation. This technique can be problematic in some cases because, for example, zinc trace residues may remain in the end product. However, chemical activation is preferred over physical activation owing to the lower temperatures and shorter time needed for activating material.

In view of this, these type of AC are unsuitable for aquarium usage and will leach unwanted materials, http://www.hallman.org/filter/gac.html. The aquarist who uses them may unwittingly be misled to think that the leaching is caused release of them once the surface areas for adsorption being used up.

...The carbon product may be supplied as granular activated carbon (GAC), powdered activated carbon (PAC), or in pelleted form (compressed PAC). Some carbons are activated or washed with phosphoric acid, zinc chloride, or potassium hydroxide. These chemically treated activated carbons are unsuitable for use in the aquarium. These products could leach phosphate (an algae promoter), heavy metals, or alter pH...
...Nine activated carbon products were tested for phosphate contamination. Five of these contained phosphate, including so called “marine” carbons...

In theory, AC could release or desorb what it removed, but practically, it is unlikely to occur:

...In theory activated carbon could release or desorb what it removed at some point. But practical experience with aquarium filtration and laboratory experiments show desorption rarely occurs or causes any type of “toxic release”...

The skeptical aquarist has very interesting topics to explore, worth some reading, http://www.skepticalaquarist.com/doc.../chemfil.shtml

Re-release of adsorbents. An intuitive question is: Can adsorbed substances be re-released into the aquarium water somehow? The brief answer is: No. Still, some manufacturers of filtration media offer dark hints that cast doubts on rival products. In general, to release substances from an ion-exchange medium, you'd have to flush it with salty brine, or with extremely acid (below pH 3.0) or alkaline baths. "Recharging" situations like these would never be found in normal aquarium conditions. You'll hear timid hedges like "possibly under certain circumstances" from many knowledgeable people. But the real plain answer is simply "No."

You can also differentiate the grades of AC using the specifications like angstrom, Iodine Adsorption Number, Molasses Number. Remember that AC are used in many different applications and not all AC products are equal in performance. So this may have contributed to some "conclusions" when aquarists have "bad" experiences with them.

Here is rough guideline on the selection of a carbon product:

1) No chemical activation or washing with phosphoric acid, zinc or hydroxides.
2) Macroporous structure: large pores of 30 Angstrom or above.
3) Low Iodine Number: below 600
4) High Molasses Number: above 400

I haven't had time to reaffirm the above, but see no reason to doubt it since the article writtten is pretty "sound" (when checked with other various sources, e.g. Wikipedia).

I will continue with Purigen tomorrow, as it is pretty late now.

[hebi]

wow thats a lot of info and i hate chemistry. haha
zenscape: how long did you use your purigen before you regenerate it? mine turned brown just a day after i put it in and now most of the beads are brown already.