Some reef aquaria have chronic low nitrogen availability. One indicator is very low nitrate. Nitrate dosing is a fine remedy, but it is possible that ammonia dosing may be more beneficial for some organisms since ammonia can be energetically easier to assimilate than is nitrate.
For this reason, I thought it would be useful to provide some DIY directions for ammonia dosing.
There are many materials that could be used for ammonia dosing, including some household ammonia solutions, but in order to give better assurance of purity, I'm electing the show directions using food grade ammonium chloride and food grade ammonium bicarbonate.
Ammonium Chloride
Ammonium chloride, NH4Cl is essentially ammonia (NH3) plus hydrochloric acid (HCl). The reason I mention that fact relates to the impact on alkalinity. Dosing NH3 followed by consumption by organisms to form tissue in a net alkalinity neutral process. I'm ignoring the fact that if it is converted into nitrate, alk is lost, because if that nitrate is later used, all the alk lost comes back.
However, the HCl that is effectively dosed will steadily deplete alk. Adding the equivalent of 50 mg/L nitrate (0.81 meq/L; coming from NH4Cl) will have depleted 0.81 meq/l (2.3 dKH) of alkalinity. That may need to be made up for in some other fashion, such as adding more alkalintiy supplement.
High quality ammonium chloride is readily available and inexpensive. Loudwolf is one brand, but there are many. Aim for food grade or ACS reagent grade. Amazon carries many Loudwolf is $7 for 4 ounces, which contains 38,000 mg of ammonium, and is equivalent to 131,000 mg of nitrate, enough to raise 100 L of aquarium water to 5 ppm nitrate about 262 times. So cost is not significant.
Ammonium Bicarbonate
Ammonium bicarbonate, also known as baking ammonia, NH4 HCO3 is essentially ammonia (NH3) plus CO2 and water.
As mentioned above, dosing NH3 followed by consumption by organisms to form tissue in a net alkalinity neutral process. The CO2 and water also do not impact alkalinity. Thus, ammonium bicarbonate is a net alk neutral way to dose ammonia.
High quality ammonium bicarbonate is also available from Amazon as baking ammonia. It is readily available and inexpensive. One brand sells 11 ounces for $15, so it's cost is similar to the Loudwolf ammonium chloride per unit of ammonia added (one needs to use more of the ammonium bicarbonate than the ammonium chloride, evening out the cost).
Stock Solution
Using either of these materials, we will make a stock solution for dosing. Keep it closed up as it will smell of ammonia and slowly loses ammonia to the air. Ammonium bicarbonate will have a higher pH, smell more, and lose ammonia to the air faster.
13.5 grams of ammonium chloride (about 3 - 4.6 teaspoons, varies by brand) in 1 L RO/DI water.
OR
20 grams of ammonium bicarbonate (about 4 and 3/4 teaspoons) in 1 L RO/DI water.
Both solutions contain approximately 4300 mg/L (4.3 mg/mL) ammonia, equivalent to 15,700 mg/l nitrate.
Dosing
Don't be overly afraid of dosing ammonia due to toxicity, but one cannot dose substantial amounts all at once. IMO, it is safe to add 0.1 ppm ammonia (equivalent to 0.36 ppm nitrate) at once to any reef tank, and one can likely add more, if it mixes in well. Don't dose it right onto a fish, but dosing 2-3x that amount at once is also likely OK. Of course, using a dosing pump to spread out the dosing is fine and may be preferable, but be sure to guard against dosing pumps out of control (e.g., stuck on). Stock solutions can be increased or decreased in potency to match pumping needs. The ammonia could also be put into an ato since exact daily dosing is not required.
To add 0.1 mg/L ammonia to an aquarium, you would need to add 2.3 mL of either stock solution to a 100 L (26 gallon) aquarium. You may need to add this amount multiply times per day to dose enough.
I'd add it to a sump, if possible, to dilute it well before it gets to the main tank. Most folks dosing ammonia wouldn't also be using media intended to push the nitrogen cycle in various ways, but if you do, dose downstream of that media.
Of course, if anything seems to react badly the first time or two that you dose, stop dosing, double check the amounts, and perhaps come back to this thread for further discussion of what might be happening.
This article has a lot more on ammonia in reef aquaria, although some parts of it may not be correct (such as the utility of products such as Prime):
Ammonia and the Reef Aquarium by Randy Holmes-Farley - Reefkeeping.com
Happy Reefing!
edit: One can use this calculator for dosing these stock solutions. Use the entry for ammonia from ammonium nitrate when using the ammonium bicarbonate. For ammonium chloride, use it the same, but dose 0.7 times the amount it says to add to the aquarium.
