What is Fishless Cycling?
The term “fishless cycling” refers to the process of establishing the nitrifying bacteria in a newly set-up aquarium without using fish which are used in the traditional cycling method (for information about cycling a new aquarium please click here).
The problem associated with using fish in the cycling period is that normally, when establishing the nitrifying bacteria in a new aquarium, the ammonia and nitrite concentrations can get so high that the fish may die. Typically, therefore, hardy inexpensive fish were used during the cycling period, but many people prefer not to subject any fish to the possibility of death from high ammonia or nitrite so a different method was called for, which resulted in the fishless cycling method.
Note: The fishless cycling method was developed before the invention of DrTim’s Aquatics One & Only Live Nitrifying Bacteria, which effectively eliminates the possibility of high ammonia and nitrite during cycling when used correctly. However, whether you choose to cycle your aquarium with or without fish, it will still take about 30 days unless you add an effective nitrifying bacteria. Using DrTim’s Aquatics One & Only Live Nitrifying Bacteria in either case will cut the cycling time dramatically.
An Easy Way to Start Your New Aquarium – Read our “Quick Guide to Fishless Cycling” here
What’s Cycling and Who Are the Nitrifying Bacteria?
Briefly, the main waste product of fish is ammonia, which dissolves into the aquarium water. But ammonia is toxic and will build up in the water unless something is done. Luckily, nature has provided the answer in a group of beneficial bacteria called nitrifying bacteria. One set of these bacteria (the ammonia-oxidizers) converts the ammonia to nitrite. But nitrite is also toxic to fish, especially in a freshwater aquarium. However, a second set of bacteria (the nitrite-oxidizers) convert the nitrite to nitrate which is non-toxic (for traditional reasons this process is called a “cycle” but the nitrate does not go back to being ammonia to complete the cycle except in special cases which are beyond this article).
The problem is that both the ammonia and nitrite oxidizing bacteria are very slow growing so it can take 30 to 45 days (usually saltwater takes longer) for the bacteria to become naturally established, during which time ammonia and nitrite can reach toxic levels and potentially causing fish death (see chart 1). Also, and this is important, in order for the nitrifying bacteria to become established, there has to be some source of ammonia added to the aquarium. Just setting up the tank and turning the filter on will not establish the nitrifying bacteria.
Fishless cycling uses an ammonia source other than live fish to establish the nitrifying bacteria.
How to Fishless Cycle
There are a few different ways to fishless cycle your aquarium which are described below. All have the basic steps of adding ammonia from some source instead of live fish and waiting until the ammonia can be converted to nitrate quickly, at which point the tank is considered cycled and you can start to add fish. To be sure the tank has cycled, you should buy ammonia and nitrite test kits and make sure all the ammonia is converted to nitrate with no trace of nitrite within 24 hours before adding fish. Beware, however, during the fishless cycling, only enough bacteria will be established to take care of the ammonia added to the tank during the cycling period. If you add so many fish that they produce a lot more ammonia than was added during the fishless cycling, you may see some ammonia and nitrite but these should disappear after a day or two – more information is given below about how to complete the process.
Using shrimp or fish food
One of the more popular fishless cycling methods is to buy a few dead shrimp at the grocery store, cut them up into chunks and add them to the aquarium. The shrimp decay, which produces ammonia to feed the nitrifying bacteria. There are a few drawbacks with this method, one being that the hobbyist really has no way to know how much ammonia is being produced by the decaying shrimp, and the aquarium does not look very good with dead shrimp laying on the bottom. Also, the organic material of the shrimp can cause bacteria blooms which turn the aquarium water cloudy. This method works but it takes time and patience and you will probably see a spike in ammonia and nitrite if you add a medium to heavy load of fish after the initial cycling. Note that some people use flake fish food instead of shrimp but this is not recommended because flake food does not have much organic material compared to shrimp and so does not add a lot of ammonia to the water, but you can use cut fish instead of shrimp. Hint: to speed up the decay of the shrimp/fish and produce more ammonia, add some DrTim’s Aquatics Waste-Away sludge busting bacteria to the tank.
Using ammonium chloride
This is the other most popular way to cycle a fishless aquarium. Simply add chemical ammonia to the aquarium water and let the process cycle. The benefits of this method are that the tank does not cloud up with a bacteria bloom and you don’t have to look at an aquarium with dead cut up shrimp or fish on the bottom. Plus you can somewhat accurately determine the amount of ammonia being added to the tank. The drawbacks to this method are that the proper ammonia solution can be hard to find and when you do find an ammonia solution you may not be able to easily determine its concentration.
Why do you need proper ammonia? Most of the ammonia solutions that are easy to find at grocery or hardware stores are for household cleaning use. They usually contain an additive for scent or something else. Never use anything but pure ammonia. Also, many of the ammonia cleaning solutions which have a heavy ammonia order also have very high pH and the smell is ammonia gas. Over time, the ammonia is leaving the solution so the concentration is changing (getting lower). Most start out between 4 and 11% ammonia but rarely is the concentration given on the bottle, so it can be hard to figure out how much to add. If you are going to use an ammonia solution, proceed cautiously at first until you have an idea of how much ammonia is actually being put into the aquarium water. For this you need to be able to accurately measure the amount of the liquid you are putting into the water. Add some solution to your aquarium, let it mix and then use your test kit to measure the ammonia concentration in the water. You want to have an initial ammonia-nitrogen concentration of 2 to 3 mg/L (ppm). Do not go above 5 mg/L.
Whatever the source of your ammonia, the following is the way to proceed. Add the ammonia solution to the aquarium so that the ammonia concentration is between 2 and 3 mg/L (but, as mentioned, do not go above 5 mg/L). Record the amount of liquid you added. If you are not using DrTim’s One & Only Live Nitrifying Bacteria, wait 2 or 3 days and measure the ammonia and nitrite. Continue measuring ammonia and nitrite every 2 or 3 days until you start to see some nitrite. This is a sign that the ammonia-oxidizing bacteria are starting to work. Add half the initial amount of ammonia you added to the water on day 1. Continue measuring ammonia and nitrite every 2 or 3 days. Around day 9 to 12, the ammonia will probably be below 1 mg/L, maybe even 0, but nitrite will be present. Nitrite does not spike until somewhere between days 14 and 20. You want to be careful adding more ammonia because you do not want the nitrite-nitrogen over 5 mg/L as this will start to poison the nitrite-oxidizing bacteria. Add a little ammonia every few days (1/4 dose), making sure the nitrite does not go above 5 mg/L. Once you start to see the nitrite decrease, it will drop pretty fast. The cycle is completed when you can add the full dose of ammonia (2 to 3 mg/L-N) and overnight it all disappears to nitrate with no sign of nitrite. Now you can start to add fish.
Using DrTim’s Aquatics One & Only Live Bacteria
The best and easiest way to fishless cycle is to combine adding the ammonium chloride with our Live Nitrifying bacteria. When used in combination, these will cycle the tank in less than one week. Again, do not add too much ammonia. We make it easy by providing a bottle of reagent grade ammonium chloride that is at a concentration such that adding 4 drops of solution to 1 gallon of aquarium water will result in an ammonia-nitrogen concentration of 2 mg/L (ppm)
NOTE – DrTim’s changed the ammonium chloride solution in Nov 2016 so it now takes 4 drops instead of 1 drop)
The procedure is to add the ammonium chloride solution, shake the bottle of nitrifying bacteria well and add it to the aquarium. Measure ammonia and nitrite the next day and record. Add ½ dose and wait 24 hours and measure again. By day 5 to 7, you should be able to add 4 drops per gallon and the next day, ammonia and nitrite will be 0.
Everything you need for successful fishless cycling
DrTim’s Aquatics best-selling product, One & Only Live Nitrifying Bacteria is the ultimate nitrifying bacteria for use in fishless cycling. Now you can put an end to “New Tank Syndrome” forever. DrTim’s Aquatics offers complete, step-by-step instructions on how to do fishless cycling using the products below
Check out the Guides and Recipe Cards for Fishless Cycling
Troubleshooting Fishless Cycling
The three biggest problems with fishless cycling are:
- cloudy water, which may even smell, when doing the cut shrimp method;
- letting the ammonia and/or nitrite getting too high when dosing with ammonium chloride; and
- a low pH value.
The cloudy water will eventually clear up but you can add a natural organic remover like DrTim’s Waste-Away to speed up the decay process. You can also change the water. Many people mistakenly think the cloudy white water is a nitrifying bacteria bloom but that is wrong. Nitrifying bacteria cannot grow fast enough to cloud the water.
The high ammonia or nitrite concentration (which by the way can sometimes occur in the shrimp method) is a problem because high levels of ammonia or nitrite inhibit the nitrifying bacteria. You need to change the water to reduce the ammonia and nitrite to get the cycle going again.
Also, if you decided not to use our Live Nitrifying Bacteria in the beginning and now want to add some to speed up the process, you need to make sure the ammonia and nitrite concentrations are under 5 mg/L-N before adding the One & Only Live Nitrifying bacteria. The bacteria in One & Only are completely non-toxic and can be added anytime (even when fish are in the tank).
The other big problem is that the cycling process seems to stall with ammonia or nitrite not dropping anymore. Usually this is due to a low pH value (less than 7.0). The conversion of the ammonia and nitrite by the bacteria naturally produces an acid that will lower the water pH. If the pH gets too low, however, the nitrification (cycling) process will stop. So if you add a lot of ammonia over the course of a week and get the cycling cranking, you can actually cause the pH to drop to a low value and ‘stall’ the entire process. The way to get the cycling going again is to simply do a 25% to 20% water change. This will increase the pH and usually gets the cycling process going again.
Lastly, do not add ammonia-removing products as this just complicates the process – let nature take its course and your tank will be ready for fish soon.