About nitrate and ammonium carbonate:

 The maximum contaminant level (MCL) for nitrate-nitrogen in drinking water in the United States is 10 milligrams per liter (mg/L). This is the amount of nitrogen in the nitrate form. The European standard for nitrate is measured as total nitrate (NO3) and has a maximum allowable level of 40 mg/L. 

Nitrate can be found in many foods, especially in some green leafy and root vegetables. The average daily intake of nitrate from food is 30–130 mg/day as NO3. 

Nitrate can enter drinking water from a number of sources, including: 

Fertilizers

Livestock waste

Failing septic tanks, drainfields, and drywells

Rainfall

Groundwater

Aquifer

Nitrate can be harmful to infants, pregnant women, and the general public. In infants, high levels of nitrate can cause methemoglobinemia, also known as blue baby syndrome. This condition occurs when the blood's ability to carry oxygen is affected, causing the skin around the eyes and mouth to turn blue. 

To remove nitrates from drinking water, you can use an ion exchange device or a reverse osmosis system. 

Here's some information about nitrate and ammonium carbonate:

Nitrate

In tap water, nitrate levels of 10 parts per million (ppm) or less are generally considered safe for drinking. In aquariums, the ideal nitrate level is 5–10 ppm, with 20–50 ppm considered too high. Freshwater tanks can have higher nitrate levels, while marine fish tanks should have lower levels, and reef tanks should have levels as close to zero as possible. 

Ammonium carbonate

Ammonium carbonate is a chemical compound with the formula [NH₄]₂CO₃. It's a white powder or block that's used as a leavening agent, smelling salt, and buffer. When heated, it breaks down into carbon dioxide and gaseous ammonia. 

Here are some other things to know about ammonia and nitrate:

Nitrite

Nitrite is even more harmful than ammonia and should be kept at 0 ppm. Nitrite can stress fish and even cause them to suffocate. 

Ammonia

In aquariums, an ammonia+ammonium level of 0.25 ppm or less is considered "undetectable" and indicates a healthy aquarium with low bacterial counts.