Have to agree with truck, while in fish keeping defining a method as "proper" probably isnt the best thing to do, using excel as an algaecide is curing the symptom and not the actual issue. People prefer to do this because it requires less patience and effort, but most of the time, the problem does not solve itself and as soon as you stop dosing excel, it comes back.
This is what excel is:
[URL="http
/en.wikipedia.org/wiki/Glutaraldehyde"]http/en.wikipedia.org/wiki/Glutaraldehyde[/URL]. It's no surprise that it harms invertebrates, and probably isnt great for fish over the long term.
However, for some tanks I'd go ahead and presume it's doing very minimal to no damage, depending on how fast the plant's can take it up. I'm going to further presume that this is why reviews of it tend to be so contrasting ("it killed my shrimp!" compared to "it got rid of my algae and has improved plant growth!"). I think it's a great product for tanks such as iwagumi planted scapes, as it quickly deals with algae problems and helps plants, allowing the designer to finish the scape and move on to a new one, but don't recommend it for tanks that are intended to stay long-term.
I read that page in the past and decided to use it anyway (not as an algaecide, but to provide plants carbon), and noticed no side affects on any fish, but as I mentioned, I used it recently and it killed quite a few shrimp.
heh
