# Activated Carbon and Purigen vs Yellow H2O and Fishy odor



## Jarrod987 (Aug 18, 2015)

Wanted to test weather Bulk Reef Supplies ROX and later Seachem's Purigen did a good job removing yellowing compounds known as tanins from the water. I notice lot's of people use a mix of both Activated carbon and Purigen. So doesn't the manufacturer of Purigen.
Been watching water treatment videos for tannins. They are reportedly hard to remove and yellow water from 1 spot in a stream can be different then the yellow water from just a few miles down stream and a different media would do better in each case. All depends on what plants they were. Commercial Tannin removing filters and are ion ex-changers which release sodium. This could accumulate so obviously do not want to do that.

Started with 20 gal aquarium with fairly yellow water. 15 gal is actually water.
4 spoonfuls of ROX Activated Carbon and 1 week later the yellow had been reduced a fair bit but still yellow is detectable in the white bucket with no problem.
Replaced ROX with 2 new spoon fulls and ran for 16 hours. on half the sample. Save the other half for comparison.

Result was that yellow was reduced again but still detectable in white bucket. The blue color of the water is starting to show through. Other sample is definatly more yellow.

Replaced ROX with 21 oz retail bag of Purigen rated for 400 liters (100 gal). That is way over kill but so wasn't ROX. Purigen comes in a chemical resistant bag which makes a lot of the water bypass it in the up flow reactor. I am not happy about that but if it works, maintenance will be much easier.

After a few hours the Purigen seems to have the water less yellow then the other sample from the ROX. Can't tell the color easily, going to compare to a bucket from the tap at the end.

After 8 hours Purigen seems better then ROX after 16 hours. Seems about 30% as yellow and is hard to tell the color of the water now. Will compare to tap but going to let it run a while longer to see how close I can get. Looks like there is a limit to how many tanins can be removed.
I have been watching water treatment videos about tannins and it seems different medias do a better job on different tannins even a few miles down the same body of water. Different plants might make a different type of tannin that a different media might do better at removing. I can see where maybe activated carbon might remove one better and Purigen might remove another better.
Something I noticed is that the Purigen still has a "Fish Tank Smell" tot he water but the ROX sample doesn't have that smell anymore. I can see why these 2 are used together.

After about another 9 hours Purigen wins. The eater is defiantly less yellow the the ROX water. It is pretty much indistinguishable from the tap water.Has no fish smell (trimethylamine) detectable. There is a slight fishy odor from the ROX. ROX may have been able to remove the rest with more time.

From my research and Talking to Seachem, Many people run both. Purigen for the organics like tannins, amines, and of course to remove the molecules that eventually break down into nitrate and phosphate. They run activated carbon to remove toxins and heavy metals (bound to humic substances). It seems a little more pricey and time consuming but beats massive water changes that do not really get it done as well. This will defiantly allow smaller water changes less often and superior aesthetics of the water column.


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