how much ammonia to add when cycling

[orthikon]

I will be doing a fishless cycle on my 20 gal long and I was wondering how much ammonia to add to it to bring it up to the 5 ppm level.

Let's assume that the concentration is 28% (ACS grade) so I can get a minimum amount to add.

I remember from my chemistry that you could figure this out by stoichiometry but unfortunately the procedure escapes me. If anyone (from memory) can remember how many mL they added that would be great if you could share.

I am aware of the method of adding 4-5 drops of ammonia everyday until we hit the 5 ppm level but that seems to be too slow for me.

TIA

 

[joephys]

You don't need it to be dead on at 5. Just add like a teaspoon at a time until it is about right, then just remember how many you added.

 

[rrkss]

You could work it out rather easily. NH3 = 17 g/mol and H2O = 18 g/mol. ACS Grade Ammonia is 28% NH3 by mass (If I recall that is 14.8 moles/Liter but I am too lazy to work it out so don't trust that figure 100%). 5 ppm = 5 mg (1 mg = 1 x 10^-3 g) of NH3 per liter of water. Figure out how many liters of water is in your tank and calculate the amount of NH3 to add based on the data above. An easier way is to add 2 drops of this solution to the tank, wait 10 minutes and test. Lets say that the test comes back at 2 ppm. Now you know that each drop raises the ppm by 1. 5 / 1 = 5 or 5 drops per 5 ppm. Much easier than some stochiometry.