Re: NO3 and PO4 in Takashi Amano Aquaria

[Chuck H <grendel at usit_net>]

John Fitch wrote:

> There are two further measurements given [in Takashi Amano's TAG article], 
> which I hope someone will
> explain. They are TH of 20-40 mg/l and COD of 4-6 mg/l.  Thanks.

Hey John,

I suspect TH = total hardness.  COD = chemical oxygen demand.  It's defined 
as the amount of O2 required to oxidize both inert and bio-available 
organic compounds into CO2 and water.  The decomposition process uses up 
dissolved oxygen (DO) that fish and other animals need, so I assume that 
Amano-san uses COD as a measure of water quality (lower = cleaner), but he 
may have other motives.
--
Chuck Huffine
Knoxville, Tennessee