# Does Methylene Blue expire?



## proaudio55 (Oct 20, 2011)

I did a google search and found this:

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*STABILITY *
_Methylene Blue is stable indefinitely in the 2.303% solution. Aqueous solutions show very little, if any, decomposition even when exposed to sunlight._

http://www.novalek.com/kordon/methylene_blue/index.htm
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If it said something about decomposing or converting to _______________ then you should be concerned. But methylene blue seems to be a fairly stable chemical.


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## christian_cowgirlGSR (Aug 2, 2011)

That's what I needed to know! Thank you!


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## NWA-Planted (Aug 27, 2011)

just a FYI, but you may check out coppersafe from mardel, treats the same thing as mehtylene blue... but does not stain your silicone or anything else for that matter.


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## christian_cowgirlGSR (Aug 2, 2011)

NWA-Planted said:


> just a FYI, but you may check out coppersafe from mardel, treats the same thing as mehtylene blue... but does not stain your silicone or anything else for that matter.


I wish I would've known that earlier. I would've gotten that instead of the M.B.


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## m00se (Jan 8, 2011)

Wipes out inverts, too...What are you trying to treat?


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## christian_cowgirlGSR (Aug 2, 2011)

I'm not trying to treat anything right now. After my recent bout with something that could've been a mild form of columnaris, a fungus, or a bacterial infection, I thought I'd better get some medicines to keep on hand just-in-case. I plan on using it for a dip/bath for infected fish in the future.


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## williamsonaaron (Jan 27, 2010)

christian_cowgirlGSR said:


> I'm not trying to treat anything right now. After my recent bout with something that could've been a mild form of columnaris, a fungus, or a bacterial infection, I thought I'd better get some medicines to keep on hand just-in-case. I plan on using it for a dip/bath for infected fish in the future.


Most common issue in aquariums as I have foudn is bacterial infections and good lord there are a variety of them. The only meds I keep on hand are marcyn I and Maracyn II they are great for preventing infections and II will pummel columnaris..


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## NWA-Planted (Aug 27, 2011)

christian_cowgirlGSR said:


> I wish I would've known that earlier. I would've gotten that instead of the M.B.


I really like it, its a great parasite clearer thing, dont know if I mentioned above but its supposed to stay in the water column for 30 days (thats probably barring water changes)


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## m00se (Jan 8, 2011)

+1 for both Maracyns. Also Ich Attack by Kordon is good to have on hand. It gets the ich and works on fungus too. Those are in my medicine cab. You can get bulk erythromycin (Maracyn) on e-bay or Cheaper here.

I haven't found a good source for Minocycline (Maracyn 2) in bulk.

Good Luck


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## GUH (Dec 7, 2016)

Hello !
The stability of Methylene blue in water is a function of its concentration. Low concentrations in the range 0.1-0.05 µg/ml is unstable at ambient temperature and light. After 20 hours the absorption spectrum with lambda max = 664 nm has changed completely. A new absorption spectrum with lambda max = 530-540 nm has been formed.
A solution at 0,4 µg/ml shows the same degradation, but more slowly.
I have no absolute explanation to this, but light accelerates the break down process. In my experiments I have used Milli-Q water and the bottles have been stored with stopper.

Gunnar Hagelin
Dr. philos


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