Re: [APD] canister filter media advice?

["S. Hieber" <shieber at yahoo_com>]

I think there are two myths about charcoal:
 
1) that it does much to filter an aquarium -- if you have a lot of it, t does filter a lot of organics provided that the activated carbon is high quality and less than about two weeks exposure to the aquarium water. After that, biofilm tends to coat the surface and defeat activated carbon's ability to adsorb. It does make a decent biofilm-carrying medium. If you have a short term build up of organics in the water, a water change going to be as effective and probably less work than disassembling and assembling your filter.
 
2) that it removes minerals from the water -- activated carbon is an exceptionally poor filter for minerals -- since it works primarily by adsorbtion, it's those nice long, clunky organic molecules that tend to be grabbed. There's a minor effect on certain "heavy" metals compounds but activated carbon is notoriously inept at grabbing salts or minerals in general. For example, use all the activated carbon you want and It shouldn't affect your iron levels at all.
 
The same is true of charcoal that is not high quality activated carbon except that the lower quality stuff has almost no ability to filter anything at all -- it's just to dense.
 
So my recommendation is to use activated carbon for short periods to remove certain aniline dyes (e.g., malachite green used as a medicine) or organic medical compounds and medicines dissociate and bond with organic compounds in the aquarium. But there's generally no value in it as a long term, general filtering medium.


Poly and various densities of reticulated foam (that semi-stiff sponge stuff used for powerheads and filters) are good as mechanical filters but you have to be sure to change them when it becomes loaded or it can seriously restrict filter water flow. Sponge material is realtively easy to rinse and re-use.

The super expensive bio-media -- probably not necessary in a well planted aquarium since the plants are going to grab the nitrogen -- so the cheaper stuff like clay, lava rocks, old carbon, etc shuld work just fine for most situations.
 
sh
 
* * * * * * * * * 



----- Original Message ----
From: Rebecca Perry <rebecca at sourpuss_net>
To: aquatic-plants at actwin_com
Sent: Thursday, November 30, 2006 3:35:33 PM
Subject: [APD] canister filter media advice?


Hi there,



Newbie here with (probably) stupid question: I’m setting up my first serious
plant tank and trying to decide what kind of filter media to use in my
Fluval 204 – I’ve settled on the pre-filter stuff and the bio-max, but I’ve
got one more media compartment to fill. Walstad says not to use charcoal,
nor any very fine media, with a soil substrate (which I will be using under
natural gravel.) So what does that leave? Poly Wool? Something else? Or can
I just leave that third chamber empty?



Any advice would be greatly appreciated. I’ve been keeping fish forever, but
I’m new to aquatic gardening, so I’m not a total newbie; however my research
on this subject has turned up many conflicting opinions on these issues.



Thanks,



Rebecca


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