Re: sulfate and H2S

> From: Craig Bingman <cbingman at netcom_com>
> I am very interested in the issue of sulfate content of water, and its 
> relationship to H2S formation in the substrate.  If anyone has data on 
> this effect, anecdotal or otherwise, I would love to hear about it.

Sulfer is one of the macro nutrients necessary for plants to grow
and is one of the components of organic material which is why H2S
or FeS is one of the products of decay. My suspicion is that the
concentration of sulphate ions in water is not normally high enough 
to support a serious colony of sulphate anaerobes in the substrate.
Normal diffusion of oxygen into an otherwise inert substrate
would take oxidize the low levels of H2S from sulphate diffusion
into the substrate.

The presence of sulphates in fish poop and organic material in
a substrate is another matter. Ordinary soil contains plenty of
iron which will react with H2S. FeS is pretty stable.

My feeling with observations on my relatively high organic
substrate is that it is not very optimal for most plants however
the dangers may be somewhat exaggerated. I suppose conditions
could deteriorate if there wasn't a lot of plants in the
aquarium to maintain oxygen in the substrate by the transpiration
ducts of the plant stems and roots.

I think there is sufficient S in the aquarium from fish foods
that its probably unnecessary to use sulphate fertilizers but
this is educated speculation. Can anyone offer more data??