# How long does Excel last once seal is open?



## AquaNeko (Jul 26, 2009)

Also how long does it last if sealed. Thanks.

Longer the better.


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## qwerty (Dec 15, 2009)

*shrug* long.

Far as I know people tend to just go for the biggest bottle they can find and use it for about a year or two until it runs out...


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## Mr Fishies (Sep 21, 2007)

It's derived from chems used in labs as a fixative/sterilant (kills stuff) so it's shelf life, if kept sealed and not allowed to evaporate, would probably be on par with something like rubbing alcohol.

At the very least it'd be counted in years I bet.


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## AquaNeko (Jul 26, 2009)

So if it's opened (I opened it already but sealed it tight) can I still count on it for years? I got a 500mL bottle. Plan on using it on a 5.5gal and 10gal. Any idea on how long the bottle will last based on say first week daily dosing then afterwards every other day dosing to spread it out some.


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## Mr Fishies (Sep 21, 2007)

AquaNeko said:


> So if it's opened (I opened it already but sealed it tight) can I still count on it for years?


My "educated" guess is yes, if not allowed to evaporate. When I said sealed, I meant as in cap screwed on tightly.



AquaNeko said:


> Any idea on how long the bottle will last based on say first week daily dosing then afterwards every other day dosing to spread it out some.


C'mon, I know it's the weekend and people don't want to work on Saturday, but you can do the math as easily as I can.  Calculate your daily or weekly dose (X ml's) and divide 500/X=Y. You get Y weeks or days.


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## kaegunim (Jan 15, 2010)

I am not sure what seachem suggests, but we keep our lab gluataraldehyde solutions in the fridge in brown glass, and they are good for a couple of years.

At high concentrations (we use 25%) it will apparently react with atmospheric oxygen - you would know as it will devellop the fruity smell characteristic of esters. 

However as excel is quite dilute, the rate of reaction will be proportionally lower. I don't know that there would be any problem with the older solutions, save that less of the carbon may be bio-available...


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## AquariAM (Jan 28, 2010)

Mr Fishies said:


> My "educated" guess is yes, if not allowed to evaporate. When I said sealed, I meant as in cap screwed on tightly.
> 
> C'mon, I know it's the weekend and people don't want to work on Saturday, but you can do the math as easily as I can.  Calculate your daily or weekly dose (X ml's) and divide 500/X=Y. You get Y weeks or days.


I failed math.


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