Some of the most frequent questions we receive around here are, "What filter media can you use to remove the organics and other nasty stuff while keeping the tint in your water? How do you keep your tanks clean while keeping them brown? What's your secret?"
It's no secret, really. Just science.
Seachem Laboratories makes a wonderful filter media which can do the trick. It's an "organic scavenger resin" called "Renew."
"Huh? What's an organic scavenger resin?", you ask?
"Organic scavenger resins" are polymers (resins) that react with specific by-products, impurities, or excess reagents produced in a reaction. In other words, they remove some things and not others. Perfect for our needs! Renew will not aggressively remove tannins and humic acid. It will remove organics and particulates and will also help control ammonia, nitrates, and phosphates. Being less aggressive than carbon, it's well-suited for tinted tanks and planted aquaria, because it leaves the color bodies and trace elements required by plants present! It is effective for about 30 days, after which time it needs replacement.
Ohh, interesting, right?
This material won't raise the pH of our water like carbon can. Renew allows for control of organics without total depletion, as with more aggressive media such as carbon, etc. The "dose" is 250 mL for each 120–160 L (30–40 US gallons) of aquarium capacity. Renew comes in a convenient 1 L bottle, enough to do the trick for up to 605 L (160 US gallons)! For a tinted aquarium, it's the only media you need to use on a continuous basis, from our point of view.
So, the answer to the burning question, "What's the most useful chemical filtration media in a tannin-stained aquarium?" in our humble opinion, is Seachem Renew. We love the stuff, and have been using it for some time. It's our "media of choice" for the tinted aquarium!
So, go ahead and add those leaves, throw in that wood, and a few seed pods while you're at it...and know that your tank is protected from excessive accumulation of organics by this efficient organic scavenger resin!
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