# Question about excel or fertilizers



## howie (Jan 5, 2007)

I don't understand why overdosing with Seachem Excel or fertilizing a tank with hair algae problem kills it. Can someone please explain?
Doesn't it inflame the problem? As you are adding more nutrients for that algae to consume?


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## hoppycalif (Apr 7, 2005)

Excel acts as an algaecide, for whatever reason. So, adding overdoses of it usually kills algae, but it also kills some of the simpler plants, like egeria and vals. Some algae bloom as a result of a shortage of a fertilizer element - green spot algae shows up with shortages of phosphate, for example. So, if we clean up the existing algae and increase the dosing to eliminate the shortage the algae shouldn't come back.

Algae are genetically programmed to start growing from the spores whenever the conditions are such that there is a high probability that the algae can grow to maturity and reproduce. (This is in natural settings, not in the tank). So, there are several cues the spores react to, one of which seems to be a sudden ammonia increase, and another seems to be wildly fluctuating CO2 concentration in the water. The presence of fertilizers doesn't seem to be one of the cues - just the absence of certain ones.


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## Tonka (Mar 20, 2004)

I think that this is a very good question.

Fast growing plants allow us to cull leaves that have been affected by algae while maintaining or even improving our aquascapes. There is thus a perception that optimum levels of nutrients allow plants to "compete" with algae.

I wonder if the glass and substrate, including rocks, wood, and sunken pirate ships, would have the same amount of algae even if the plants weren't growing well?


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## howie (Jan 5, 2007)

Thank you hoppycalif! Your explanation makes perfect sense. I just have one more question. I have dwarf hairgrass and Vals. If I use just the recommended dosage, will it kill my algae problem but not kill my hairgrass? My hairgrass problem is not too bad.


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## hoppycalif (Apr 7, 2005)

My experience with vals is that they all died back with a 2X dosage of Excel, but they also regrew from the roots. It took a few months, but it looked like none of the plants were permanently damaged. I haven't tried growing hairgrass yet, so I can't comment on that.


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## John N. (Dec 11, 2005)

I think Hoppy hit it on the head with Excel and the algaecide properties. 

When I overdosed with excel, my jungle vals turned red and died back, but like Hoppy's they recovered after the treatment. Dwarf hairgrass is able to withstand the overdosing of excel. I'm currently adding more than I need in my nano, and the hairgrass looks healthy and is growing fine.

-John N.


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