Pure ammonia

[haddock]

Hi everyone,
I am getting a 40G tank delivered in a few weeks and would like to try a fishless cycle. I work in a lab so I have access (sneakily ) to pure ammonium hydroxide. I have read the stickies on this but they talk about using drops of ammonia solution. As I will be making this solution up from powder I need to know what concentration to make it (or molarity for any boffiny types!).
Cheers!

 

[The Mohave Kid]

I'm new to the fishless cycle ... but why Ammonium Hydroxide ... instead of lets say an ammonia solution ??? I would think the hydroxide would drop pH quite a bit ...

If you want X ppm of anything in your tank then you need to add X mg / liter to your tank.

So .. just for example ... if you wanted 4 ppm of ammonium in your tank ... then you would need 15.2 mg of ammonium hydroxide for each 3.8 liters or per gallon.

1 gallon = 3.8 liters.

4 ppm Ammonium per gallon = 3.8 liters X 4 mg / liter = 15.2 mg / gallon.

The concentration of the solution you use to deliver the ammonium is really up to you .... Right ??? ... but I'd check the pH situation out and add it slowly and test to slowly build up the level to where you want to be.

To tell you the truth why don't you get some ammonia in the supermarket for a buck or two

Good Day .... B)

 

[nonot8946]

If you make it too concentrated, it will be tough to dose accurately. I think the ammonia I'm using right now is 1-2%, that seems to work alright for a medium sized tank.

 

[haddock]

Mohave Kid you went to some effort there - thanks! Yeah, the pH thing is a very good point. I should have thought of that. That's what happens when you spend more time surfing fish web sites than in the lab!
Some of the solutions mentioned in the fishless cycle stickies are ammonium hydroxide. Come to think of it isn't ammonia in solution always ammonium hydroxide?

Anyone?

 

[haddock]

Further to the message above, I found this. Basically even pure ammonia will lower pH. Whether it is enough to significantly alter the pH of a large volume of water, I dunno?

"The polarity of NH3 molecules and their ability to form hydrogen bonds explains to some extent the high solubility of ammonia in water. However, a chemical reaction also occurs when ammonia dissolves in water. In aqueous solution, ammonia acts as a base, acquiring hydrogen ions from H2O to yield ammonium and hydroxide ions.

NH3(aq) + H2O(l) NH4+(aq) + OH-(aq)

The production of hydroxide ions when ammonia dissolves in water gives aqueous solutions of ammonia their characteristic alkaline (basic) properties. The double arrow in the equation indicates that an equilibrium is established between dissolved ammonia gas and ammonium ions. Not all of the dissolved ammonia reacts with water to form ammonium ions. A substantial fraction remains in the molecular form in solution. In other words, ammonia is a weak base"

 

[The Mohave Kid]

Right ... .. and I believe a low pH shifts the equation above more to the ammonium side (pH=7) ....

Good Day ...