Question about ammonia

Flamed_Razor · Nov 14, 2014

I came across an article about about ammonia and this is what it said
"The pH (power of Hydrogen) level in your tank determines how many of the ammonia molecules are toxic or non-toxic. If your tank water pH is at 8.3, most or all of the ammonia molecules will be the NH3 (toxic) variety. If your pH is 7.5, the same amount of ammonia in your tank will be 1/5th as toxic because about 4 out of 5 of the ammonia molecules will be the NH4 (non-toxic) variety."
Just how much of this is true? I always thought Ammonia harmful at high levels regardless of the pH levels

maxxin69 · Nov 14, 2014

[FONT=Arial, Helvetica, Geneva, Swiss, SunSans-Regular]"The fact that low pH reduces ammonia toxicity is fortuitous for fish culturists. Fish produce both carbon dioxide and ammonia as waste products. As you have learned, carbon dioxide reacts with water to form carbonic acid. In the absence of buffering this lowers the pH of the water lowering the toxicity of the ammonia that is also being produced. Using the calculator, you can see that while 10 mg/L total ammonia is non-toxic at a pH of 6.5, only 0.5 mg/L can be tolerated at 8.0! While recirculation aquaculturists may count on low pH to reduce ammonia toxicity during hauling and other times of brief confinement, they cannot use this effect in their systems because of the negative effect of low pH on nitrification as explained below."[/FONT]
[FONT=Arial, Helvetica, Geneva, Swiss, SunSans-Regular]Apparently very. Anything at high enough levels will kill anything. pH is more or less a neutralizer of unionized Ammonia. While I still don't think that ammonia should be detectable in any tank outside of cycling, it's interesting. [/FONT]

Flamed_Razor · Nov 14, 2014

Ok, think I understand the way you explained it better then the article. Doesn't temperature play a roll too?

maxxin69 · Nov 15, 2014

Yes it does. As temperature increases so does the toxicity of the ammonia, or rather just allows more unionized ammonia in the water.

Randy Holmes-Farley · Nov 15, 2014

FWIW, I think that quote in the original post was from a freshwater article, and it doesn't translate correctly to seawater.

It is not correct as written if applied to seawater. Free ammonia (NH3) does not predominate in seawater until the pH is well up into the 9's.

The quote is also oversimplified, but that is normal for hobby stuff.

However, ammonia toxicity in seawater does increase as the pH is raised, and is much less of a concern at pH 7.5 than at pH 8.5 for the same total ammonia concentration.

This has much more:

Ammonia and the Reef Aquarium by Randy Holmes-Farley - Reefkeeping.com

Flamed_Razor · Nov 16, 2014

Thanks Max for the help

Randy, don't recall where I read it. To be honest I never paid attention to ammonia after the cycling is finished. Your articles are always informative. Glad to have you here. Thanks!