# Excel feeds plants, but not algae!?



## John N. (Dec 11, 2005)

This question was brought up on another forum, and I figured APC would be a great place to discuss this just in case it hasn't been discussed ere before. According to the quote below from the bottom of this page, Seachem Excel does not feed algae with a carbon source. Why not?




Gregory Morin said:


> *
> Can algae feed on Excel?
> *
> No. I'm sure this may raise a few eyebrows since at face value this would be a reasonable expectation. But, for reasons Uncle Sam won't let us discuss, all I can say is that algae can't feed on Excel and I will leave it as an exercise to the reader to deduce why this is the case (big picture folks, no chemistry involved.


Anyone have any thoughts or reasoning why plants only benefit from Excel, whereas algae will not/cannot?

-John N.


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## epicfish (Sep 11, 2006)

Glutaraldehyde is moderately toxic to aquatic animals and moderately to highly toxic to algae.
http://www.npi.gov.au/database/substance-info/46.html

Glutaraldehyde is readily biodegradable (OECD 301A and 306 guidelines) and is not classified as a cause of long-term damage to the aquatic environment. One of few biocides that meet the criteria to be called readily biodegradable, glutaraldehyde is very suitable for use in aqueous systems discharged to the environment via water treatment works. Although glutaraldehyde in high concentrations (25 percent active and above) can be moderately toxic to algae, its short life in the environment ensures minimal effects on aquatic life.
Glutex Product Portfolio

Of course this is my scientific mind thinking. Maybe since algae is filamentous or single-celled, it's more susceptible to Excel (main ingredient: isomeric glutaraldehyde, which is toxic to many things in high concentrations). Quite possibly the same reason why riccia is also susceptible to higher doses of Excel?


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