Let's take a look.
Removes organics, that's good.
Removes NH4, that's great.
Removes yucky yellow color from tannins, that's even better.
Supposely removes traces, that's bad.
Turns to biomedia after 1-2 months.
Amano uses it and seems to think about the same things about it.
I'd give it two big green thumbs up.
Some ADA AS is more tanninsish than others BTW.
Seachem purigen is a good alternative to carbon if you are concerned about traces. I like using it in my Discus tank to control organics that build up despite the weekly 80% water changes. It has a water clarifying effect just like carbon, but it will not take the traces out of the water. Another thing that I like about it is that it can be recharged with bleach when it is exhausted and used over and over again.
I find purigen cheaper in the long run because I can reuse it over and over endlessly- at least so far. True that is is not a good biomedia, but then again thats what true biomedia is for. I guess it all depends on your application. For myself I have two filters one for biofiltration and the other for mechanical/ chemical so it works for me. I guess it also depend on if you plan on only using the carbon once (like when setting up a tank) and then leaving it in there, then yeah Purigen would be a waste for that I think. It's just a good alternative worth mentioning.
The only issue I have a problem with is the notion that traces are really removed by carbon and given it last aboput month anyway, then goes south, what's the issue?
The effects are only termporary at best and not significant at worst.
I think it's toughb to shwo there's a big issue with this unless you add AC all the time etc, I think Zeolite for NH4 removal is better.
For tannins, water changes/AC works very well.
Then you remove the media, then add the traces, fairly simply if you have a sump etc.
I tend to use AC incidentally. Usually powdered as an overlay with a diatom filter if I can't get a new setup to clear. Usually it will clear on its own.
Where I get strung out on AC is the Vast difference in qualities available over the counter. I tend to buy by the bucket or barrel, but I just don't use it often enough these days to justify buying a 55 barrel.
Given our local water quality I tend to strip everything and reassemble it as needed, but I'm forced to admit it's anal and likely a complete waste of time. Old habits die hard ! Plants are pretty resilient, and do better work than I do.
I still think AC makes a fine high porosity matrix for denitrification, so it may very well be a win/win situation.
Should the AC be switched out every 1-2 months also like my filter instructions tell me to? Or should I just put it in there when I first start the tank then leave it in there for the life of the tank....
I use it maybe once a month to clear the water i leave it in maybe 2 days then remove it when water is crystal clear. I do a 50% water change a week on sunday that usually is enough to do the trick other than the small amount of cheap carbon in my hob filter pad. In my testing i dont notice any changes in my water testing if you use it remove it when its spent.
I think another question at hand needing discussion over the use or not of carbon/chemical filtration on a planted tank is it's continual use in the filter. What I mean is that the way I have used it in my fish only tanks was to change it monthly to maintain it's chemical filtration capacity. Wondering whats the general concensious on the pros/cons of carbon in that scenario?
Myself using Purigen in this manner now for several months, my unscientific observaton is that the water looks more crisp, the fish seem happier, the plants pearl more, and that scum on the surface of the water (we all know and love) is little if any.
I suggested this idea when I discussed PPS with Ed and others on APC a couple of years ago, only to be scoffed at.
And I'm the closed minded one
Within the context of PPS, and not doing water changes, then perhaps such chemical removal of organics is wise at higher growth rates that greatly exceed the normal bacterial rates of decomposition.
We and anyone worth their salt knows that large frequent water changes will drive a system faster and cleaner, pearling more etc for pretty much the same reasons, so the idea, the notion of chemical removal is also based on that premise.
But some with apparently far less knowledge and understanding about leaching, decompstion and biogeochemistry seem not the think so, based of their claims, such observations you have seen do not exist according to their hypotheses.........
You can observe the same things you have seen, both with the AC or the PG or the large water change.
You can mix them, add them at various times.
I think you will start to see some issues with traces over time with AC, but perhaps PG will be okay.
Try it and see.
I just do a water change weekly rather than change the AC etc monthly , that takes care of it. PG can be used and less issues with traces from what's said.......
But a controlled study?
Few have done it, if anyone and I'd be awful, skeptical of the methods done if such a claim came forward
But I think on a more practical level, try the PG, and keep doing the weekly WC and see if you think over time, that it helps.
I will say this, it will not hurt using PG.
So that's not a bad thing.