Free Ammonia vs. Total Ammonia

[Bleeding]

Can anyone explain to me the difference between free ammonia (NH3) and total ammonia (NH4+)?

I think i read that free ammonia is more deadly, and total ammonia, or ammonium, is relatively harmless?

In recent posts, i have been trying to solve a horrible water problem with ext. high ammonia levels. Just got a new eheim 2028 running on the tank, and the ammonia test kit (which is a seachem kit with the little yellow sensors) is reading that i still have high total ammonia levels, but only trace amounts of the free ammonia. By trace i mean .01 ppm.

 

[Bleeding]

?

 

[fishmaven]

Can anyone explain to me the difference between free ammonia (NH3) and total ammonia (NH4+)?

I think i read that free ammonia is more deadly, and total ammonia, or ammonium, is relatively harmless?

According to the book_ Water Chemistry for Advanced Aquarists _ by Guido Huckstedt, TFH, 1963, ammonia and ammonium vary depending on the pH.

Here's a chart by him:
pH value ammonia % ammonium %
6 , 0 , 100
7 , 1 , 99
8 , 4 , 96
9 , 25 , 75
10 , 78 , 22

Guido goes on the explain that 30-40mg/l of ammonium in low pH is not exceptional and by doing a 50% water change with water of a higher pH toxins could go from low or insignificant to lethal.

"Sensitive fish react at 0.2mg/l, more robust fish at 0.5mg/l. At best 2mg/l can be tolerated for hours without damage; at worst,1mg/l proves lethal in a short period of time."

Testing ammonia should be done in a high pH solution OR referenced to a chart. Add to that the different sensitivity of the fish, the size of the fish, the varying levels of CO2 and oxygen, temperature variants and other things, you find it's not just a simple matter of numbers.

Sometimes the effect of the water change is referred to as pH shock. As you can see it's NOT pH that has "shocked" the fish, it's the changing levels of ammonia vs ammonium within the total ammonia number. Dan

Sorry, I couldn't get the chart to look right. I did separate the columns by a comma.

 

[Big Roc]

Did you ever think that your NEW filter might not have any boilogical buildup in the media?? I hope you don't have any fish you care about in that tank because you may just be re-cycling you tank again.

 

[RadleyMiller]

When pH is > 7.0 ammonium becomes ammonia and is more toxic.

The free hydrogen ions in acidic water (pH < 7.0) bond with the ammonia to make ammonia NH4+, which is less toxic.

Ammonia is still toxic no matter if it is NH3 or NH4+ and a cycled tank should have no trace of each other. Your tank has not cylced yet.