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There are a huge number of beginner hobbyists that have Googled aquarium cycling and come up with ammonia as being the perfect feed for fishless (no fish in the tank) cycling. This is largely because of the determined efforts of one supplier (Dr. Tim) of very overpriced solutions of ammonium chloride.

Most experienced hobbyists, including the author, don’t do cycling with ONLY ammonia as the feed. For whatever reason, cycling with only ammonia seems to take longer and has more variability than cycling with food. This appears to be because beneficial bacteria need many things to metabolize and multiply. In addition to ammonia, they need phosphates, sulfates, iron, carbon dioxide, etc. Pure ammonia doesn’t supply these nutrients, fish food does supply them.

Also, all fish food will have some beneficial bacteria in it. So it adds a tiny amount of “seed” material (inoculate). Ammonia has no “seed” material at all in it. The YouTube video maker “Girls Talk Fish” (great channel!) tried to do a cycle with Dr. Tim’s ammonia solution. She took the level of ammonia up to 4 ppm and then added more ammonia when the level dropped to 0.5 ppm. After nine weeks (yeah, 63 days) the ammonia added was still there after 24 hours. The tank wasn’t cycled even after 63 days. So she stopped the test. This is not unusual.

The other ignored factor is that there are two distinct types of “beneficial bacteria”. The first is the autotrophic bacteria that convert ammonia to nitrate. These are what are normally thought of as the only beneficial bacteria.

But there is a second type of beneficial bacteria. These are the heterotrophic bacteria that decompose waste in the filter rather than in the water column. These bacteria are essential to the health of the fish because they outcompete the “bad” heterotrophic bacteria in the water column. These are the bacteria that prevent cloudy water from forming. Cycling with ammonia does not create these bacteria. This is a problem for ammonia cycling methods.

But many hobbyists like ammonia because it is “clean”. So we’ll discuss it here. There are several methods for cycling with ammonia:

Table of Contents

Method One: Household Ammonia

Buy some household ammonia. Look at the ingredients to make sure it is pure ammonia. Many bottles of ammonia have soaps in them that will kill fish. To test a bottle of ammonia cleaning solution take a water bottle and fill it halfway with water. Then add one teaspoon of the cleaning ammonia. Shake the bottle. If bubbles are created that last for more than one second, the ammonia has soap in it and can’t be used. Ace Hardware has a brand of ammonia that has no soap.

After the aquarium is set up and filled with water add a quarter teaspoon of a phosphate powder (potassium phosphate, sodium phosphate, or any one of several calcium phosphates, or a high phosphate “bloom” fertilizer like Scott’s Super Bloom 12-55-6, Flower Fuel 1-34-32 or Miracle-Gro Bloom Booster 15-30-15) per twenty-five gallons of water. This is necessary when cycling with ammonia.

Then add one drop of ammonia liquid per gallon (about 1 ppm) into the water every single day. Do no water changes. There are 100 drops of ammonia per teaspoon so a teaspoon of ammonia solution will treat 100 gallons of water.

Note that this is for a 5% solution of ammonia and household ammonia goes from 5% to 10% typically. If the cleaning solution says it has 10% ammonia only use one drop of solution per two gallons.

Method Two: Ammonium Chloride Salt

Buy some ammonium chloride (or any ammonium salt such as ammonium sulfate, ammonium phosphate, ammonium nitrate, ammonium bicarbonate, or ammonium carbonate) crystals over the internet. These chemicals are used for baking so are easily obtained from Amazon.

A 25-gallon tank will need 0.4 gram or very roughly half of a gram (1 ppm) per day of ammonium salt crystals (the amount will be the same for all ammonium salts), every day, not a lot of crystals. It is an amount that is about the size of a pea. Do no water changes.

One gram is about one-fifth of a level teaspoon. So we’re talking 1/5th teaspoon of ammonium crystals for a 50-gallon aquarium per day to get 1 ppm per day.

Method Three: Ammonium Chloride Solution

Measure out roughly 60 grams of ammonium salt (any salt) and put it in an eight-ounce or 250-milliliter bottle (240 grams or very roughly half a pound in one quart or one liter of water). Fill the bottle with water. Shake till the ammonium salt dissolves. This is very roughly an eleven percent solution of ammonia.

After the aquarium is set up and filled with water add a quarter teaspoon of a phosphate powder (potassium phosphate, sodium phosphate, or any one of several calcium phosphates, or a high phosphate “bloom” fertilizer like Scott’s Super Bloom 12-55-6, Flower Fuel 1-34-32 or Miracle-Gro Bloom Booster 15-30-15).) per twenty-five gallons of water. This is necessary when cycling with ammonia. This fact was confirmed by testing:

2.13. Test of Cycling Methods

Then add one drop of ammonium salt solution per two gallons (very roughly about 1 ppm) into the water daily. Do no water changes. Keep adding the solution every single day until the aquarium is cycled. There are 100 drops of solution per teaspoon so a teaspoon of solution will treat 100 gallons of water.

Metriaclima lombardoi - Male — Metriaclima lombardoi – Male

Method Four: Dr. Tim’s Solution

Simply buy a bottle of Dr. Tim’s ammonium chloride solution over the internet and follow the directions on the bottle. They are:

“Add 4 drops of solution per gallon to achieve an ammonia-nitrogen (NH3-N) concentration of 2 pp. Do not exceed 5 ppm in the aquarium”

In Dr. Tim’s videos, he clarifies these directions with the point NOT to add ammonia every day, but rather to test the water and only add ammonia when the concentration drops below 0.5 ppm. This will typically be about every five days initially, then it will drop to every day. Then when it drops to zero after 24 hours Dr. Tim says one’s aquarium is cycled.

Note we do not agree with the directions. We did testing which showed it was faster and better to add four drops of Dr. Tim’s ammonia per gallon every single day. To see the test and an in-depth analysis of Dr. Tim’s methodology, go to this link:

2.4.1. Dr. Tim’s Cycling Method

Common to All Ammonia Cycling Methods

Ammonia may rise to 8 ppm and higher over a few days (the exact level depends on the inoculate and the amount of feed). Contrary to popular myth, a level of over 5 ppm or even 20 ppm of ammonia does not stall the cycle. Nitrites may or may not rise to similar levels (tanks commonly cycle without any nitrite showing up).

Do no water changes.

A water change removes the food the beneficial bacteria are feeding on and growing with. So a water change will stall the cycle. Note this is only true if there are NO fish in the aquarium.

Keep adding ammonia in whatever form you decide to use every day until the measurements of ammonia and nitrites come out with zero ppm measured 24 hours after adding the ammonia. The aquarium has then completely cycled.

But some folks do cycling with ammonia by adding 2 ppm of ammonia to an aquarium and then waiting till the ammonia is reduced to less than 0.5 ppm before adding more (Dr. Tim’s directions). This will work, it just will not give a very robust or sizable colony of beneficial bacteria. If the pH of the aquarium is high (over 8.0), the fish could be in trouble with this method.

Cycling with Pee

Whenever someone on Facebook asks “what is the best feed for cycling and aquarium”. Someone will say “pee in the tank” And everyone will give a laughing Emoji at the joke. The fact of the matter is urine is a very good way to cycle a tank. When one does a fishless cycle with fish food as the ammonia source we recommend adding some urine at startup to speed things up. Speaking from experience it works!

Human urine can be used to cycle much like liquid ammonia is used. 2 drops per gallon or one teaspoon per 100 gallons per day can be used to cycle an aquarium. Humans urinate urea, not ammonia. But urea is broken down pretty rapidly (like within 2 to 4 days) into ammonia by bacteria in the aquarium, so it acts just like ammonia. The equation is:

CO(NH2)2 (Urea) + H2O + urease → 2NH3 +CO2

The big problem here is that the concentration of urea varies a huge amount depending on how much a human is drinking. This makes it difficult to control. But the average concentration of urea is 2%, roughly half the concentration of most jars of cleaning ammonia. In turn, half the urea is ammonia.

On the plus side, urine contains significant amounts of phosphate, which is something beneficial bacteria need to grow.

What Research has Revealed About Cycling

Very many university researchers have found the following:

If one can get the brown squeezings water from an established sponge filter, pour this into the water in the new tank and the cycle will occur in the fastest time possible.
Phosphate turns out to be very important to beneficial bacteria by testing. So after the aquarium is set up and filled with water add a quarter teaspoon of a phosphate powder (potassium phosphate, sodium phosphate, or any one of several calcium phosphates, or a high phosphate “bloom” fertilizer like Scott’s Super Bloom 12-55-6, Flower Fuel 1-34-32 or Miracle-Gro Bloom Booster 15-30-15) per twenty-five gallons of water.
Good garden soil from the garden or potted plants and composted manure has 19 million beneficial bacteria in one small gram. This is many times more than a whole bottle of store-bought bacteria-in-a-bottle. So a handful of soil or compost will seed a new aquarium about as well as the brown gunk from a sponge filter. Soil and compost thrown into aquarium water do cloud the water, but it clears in a week or two. Note commercial soil mixes from the garden store do NOT work (maybe they are sterilized?).
The pH for cycling should be above 7.0 and MUST be above 6.5.
Beneficial bacteria do best at a pH of 7.4 to 7.8. with some carbonates. So, adding two tablespoons of baking soda per 25 gallons speeds up the cycling. One will need to continue to add baking soda (sodium carbonate is better) to keep the pH up. Adding a bag of crushed coral to the filter is very beneficial to cycling.
Lots of aeration will both speed up the cycling process and keep the smells down (cycling can be smelly!).
The optimum level of nutrients for beneficial bacteria growth is 400 to 600 ppm of ammonia and 200 to 400 ppm of nitrite (per no less than 8 papers and two books). So high levels of either ammonia or nitrite do not stall the cycle. But note that if an aquarium has a small filter, or has poor filter media, an ammonia addition over 2 ppm per day can make cycling a very long process.
Beneficial bacteria CAN sometimes incorporate nitrate into their bodies as protein (“assimilatory denitrification”). This can give zero nitrates in a cycled tank. Plants can also give zero nitrates in a cycled tank. Thus the end of cycling is defined as when ammonia has spiked to at least 1.0 and then hits 0.25 or less 24 hours after adding some “feed” (ammonia, food, or urine). If nitrite is present it needs to hit zero before the aquarium is cycled. There does NOT need to be nitrate.
Nitrate levels are immaterial during cycling. When both ammonia and nitrite go to zero (the official “end” of cycling) do enough of a water change to bring the nitrates to a reasonable level (anywhere from 40 to 160 ppm is a fine goal)

Common Errors

Once the tank is cycled it is important not to clean the brown gunk out of the filters or to change filter cartridges. “Cycling an aquarium” is an incorrect definition of cycling. One cycles a filter. The brown gunk inside the filter on the filter media is beneficial bacteria. Clean it and the cycle starts all over again.
Plants remove ammonia, nitrite, and nitrate from the water. Since ammonia and nitrite are required during cycling to feed the beneficial bacterial growth, adding plants to the aquarium during cycling will often prevent the tank from cycling.
The most common mistake in cycling is to panic and do water changes when the water turns cloudy or green, or the ammonia or nitrite levels rise. Water changes remove the feed for the beneficial bacteria and stop the cycle. One needs to just ignore the cloudiness or the green. For more on that topic click on these links:

6.2.3. Cloudy Water

16.7. Green Water

“Snake Oil” Products

There is no use for Prime or other chemical additions during cycling. You can’t “detoxify” ammonia with chemicals. More about that in:

2.9. “Instant Cycling” Chemicals

And there was a test run on eleven different “bacteria-in-a-bottle” which showed they were a waste of money. This link reviews that test:

2.8. Bacteria in a Bottle

This test said that always takes 4 to 6 weeks for both ammonia and nitrite to hit zero with these bacteria-in-a-bottle products. The test said there will be a huge difference in the cycling time when one “seeds” beneficial bacteria (BB) with garden soil, composted manure, or brown gunk from the filter of another aquarium (6 to 12 days for a complete cycle!).

The Math of the Various Methods

Parts Per Million in a 100 and 25-gallon tank

One gallon weighs 8 x 454 gram = 3,632 grams
One hundred gallons weighs 363,200 grams
363,200 grams/1,000,000 = 0.36 grams
One part per million in a 100-gallon aquarium is roughly 0.36 gram
Four parts per million in a 25-gallon tank is 0.36 grams

1, Doing the math of the 5% Ammonia Solution

To get 2 parts per million ammonia in a 25-gallon tank you need 0.18 grams of ammonia or 0.18 x 20 = 3.6 grams of 5% ammonia cleaning solution
8/0.05 = 56 drops of cleaning solution for a 25-gallon tank to get 2 ppm.
So very roughly four drops of 5% ammonia cleaning solution per gallon will give 4 ppm.

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2, Doing the math on the solid ammonium chloride addition gives:

1 drop of water = 0.05 grams of water
1 teaspoon = 5 grams water
100 drops in a teaspoon
1 cup of water is 227 grams
Add 58 grams of ammonium chloride then fill a cup with water
58/(227-58) = 34.3% ammonium chloride
ammonium chloride is 17/(17 +36) = 32% ammonia
to get the amount of ammonium chloride multiply the needed amount of ammonia by 100/32 = 3.1
To get 4 parts per million ammonia in a 25-gallon tank you need 0.36 grams of ammonia or 0.36 x 3.1 = 1.12 grams of ammonium chloride

Metriaclima pyrsonotos Red Top Zebra - Nakatenga — Metriaclima pyrsonotos Red Top Zebra – Nakatenga

3, Doing the math for ammonium chloride solution gives:

1 drop of water = 0.05 grams of water
1 teaspoon = 5 grams water
100 drops in a teaspoon
1 cup of water is 227 grams
Add 58 grams of ammonium chloride then fill a cup with water
58/(227-58) = 34.3% ammonium chloride
ammonium chloride is 17/(17 +36) = 32% ammonia
to get the amount of ammonium chloride multiply the needed amount of ammonia by 100/32 = 3.1
To get 4 parts per million ammonia in a 25-gallon tank you need 0.36 grams of ammonia or 0.36 x 3.1 = 1.12 grams of ammonium chloride
Using a solution of 34.3% ammonium chloride in a 25-gallon tank will require 0.86 x 100/34.3% = 2.5 grams of solution or
25/0.05 = 50 drops to get 4 ppm in a 25-gallon tank, two drops per gallon, and one teaspoon solution to get 4 ppm in a 50-gallon tank.

Startpage Aquariumscience

Source: Aquariumscience.org – David Bogert