# Seachem Excel - PPM, Toxicity, and Decomposition



## spinjector (Mar 20, 2005)

I have some questions about Seachem Excel...

A few months back, someone told me that Excel works great as an algicide. And I thought Excel was a fertilizer. Turns out it's both. But in my Googling and reading about aldehydes and cyclo-what-hoozits (sorry the names escape me at the moment), I found that Excel really was both a fert and an algicide.

Does anyone have any comments on balancing these two purposes? It's kind of like when to use a knife for spreading, and when to use it for cutting, and when to use it for stabbing... =-)

I have questions about dosing - some of which may have inexact answers. I know that Seachem typically has excellent products, but are also typically and understandably vague about the details of the ingredients, due to trade secrets.

1) What's a good PPM level for Excel? I suppose this has three possible answers: daily use as a fertilizer, greater use as algicide, and finally as a spot treatment on globs of algae.

2) Use such as described here is contrary to the labeled directions on the bottle of Excel. For obvious reasons - overdosing can kill your fish.

- What level begins to be lethal for common aquarium inhabitants?

I understand, of course that some species would be more sensitive than others, and even then, it's not like it kills them instantly. Is the toxicity cumulative? Is the damage permanent? Or will fish recover from high doses?

3) I've seen much to say that Excel needs to be dosed daily - in fact, I think it even says that on the bottle.

- what's the half-life?
- do any environmental conditions accelerate its decomposition?
- what about UV light from sterilizers or metal-halide lighting systems?
- has anyone heard of dosing it with a peristaltic pump?

Thanks.


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## NeonFlux (Apr 10, 2008)

Daily use as a carbon source for your plants. Overdosing twice the amount will probably not kill your inhabitants but if you do 4x or higher it could be toxic. Flourish excel will melt vals and anacharis, so be wary


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## epicfish (Sep 11, 2006)

Post your questions in the SeaChem forum over at APC.


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## spinjector (Mar 20, 2005)

epicfish said:


> Post your questions in the SeaChem forum over at APC.


What is APC..?


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## wkndracer (Mar 14, 2009)

UV light breaks it down completely. 
As a cure for algae there's a sting here on this site about three pages long.
My experiences: 55g low tech tank staghorn problems. Dosed starter dose per label. Dosed everyday 15 -20ml 2-3x recommended level. Algae turned red, ottos ate it. What the ottos didn't eat rotted and died. Currently dose 10ml a day for the plants no algae, plants grow, 50% water changes every week same as my hi tech tanks.


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## melauriga (Feb 19, 2009)

spinjector said:


> What is APC..?


 
APC is Aquatic Plant Central, another website and forum that is very useful. Seachem has its own subforum where you can ask questions about their products and someone from Seachem will answer.


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## plantbrain (Dec 15, 2003)

Why not just email SeaChem driectly?:icon_eek:
They answer email:thumbsup:

Regards, 
Tom Barr


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## plantbrain (Dec 15, 2003)

spinjector said:


> - What level begins to be lethal for common aquarium inhabitants?


About 2x the suggest max dose.



> I understand, of course that some species would be more sensitive than others, and even then, it's not like it kills them instantly. Is the toxicity cumulative? Is the damage permanent? Or will fish recover from high doses?


No, the chemical does not accumulate like say Cu, Hg etc. There may be some tolerance built up by some plants and critters.



> - what's the half-life?


About 10-11 hours in most tanks



> - do any environmental conditions accelerate its decomposition?


Actively growing Plants, Bacteria, heat etc. Breaks down fast. Ends up CO2 and water.



> - what about UV light from sterilizers or metal-halide lighting systems?
> - has anyone heard of dosing it with a peristaltic pump?
> 
> Thanks.


NA, see half life. MH's are not going to have impact either.
You feed fish daily? Dose daily then. 
Drip etc, what happens if there's a malfunction with the pump or the rate is too high?

Dead fish => bad idea. Sure, this pre supposes there will be no errors, this is fine for say KNO3, or PO4 etc, Traces etc.........I have had the dosing pumps dump the whole thing in there, or none at all due to clogging, timer issues etc.

There are a number of ways things can go wrong there.
Wise to leave some control and back up in case of this situation, rather than leaving things wide open.

If you have a month's supply of Excel sitting there......and the timer does not shut the pump off one night.............you will have dead fish the following morning.

Correctly set up, it certainly can work fine.
Or not...........has not happened to me, but I never put more than I am willing to add all at once in the bottles supplying it.


Regards, 
Tom Barr


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