Aquarium Nitrogen Cycle and Fishless Cycling

Aquarium Nitrogen Cycle and Fishless Cycling

Part I – What is Aquarium Nitrogen Cycle?

Cycle the tank, aquarium nitrogen cycle, fishless cycle, new tank syndrome, these terms might sound unfamiliar to most beginner fish keepers who just got into the hobby. The term “cycle” about the fish tanks usually refers to an aquarium nitrogen cycle. It is the biological process of ammonia (NH3) being converted to nitrite (NO2), and then the nitrite is converted to nitrate (NO3).
Ammonia —–> Nitrite —–> Nitrate

Aquarium Nitrogen Cycle is extremely important in fish keeping hobby, and fishless cycle is the best way to do it. If this is new to you, please do not panic. We have all been there once. Just read on and you will understand everything you need to know about how to prepare your new fish tanks for your fish. :)

Part II – Why do we need nitrogen cycle in an aquarium?

Most living organisms generate ammonia as waste. Fish is no exception. Fish not only produce ammonia through their gills constantly, but also through their waste (poop), which will produce more ammonia as the waste breaks down.

In a natural environment such as a lake or a river, there is so much water that the ammonia produced by fish is so insignificant and it will be gone quickly. In a closed system such as an aquarium, ammonia is not going anywhere and it will build up to higher and higher concentration. Ammonia is poisonous. Even the smallest amount of ammonia in the water will burn the fish’s gills. Higher concentration will cause permanent damage, and eventually lead to fish’s death. It is what we refer to as new tank syndrome.

Ammonia poisoning is one of the leading causes of death for new fish, because the fish tanks they were in had never gone through an aquarium nitrogen cycle. In a well established fish tank, there are enough natural occurring bacteria to break down ammonia into nitrite, and there is also enough a different species of bacteria to break down nitrite into nitrate. Both ammonia and nitrite are toxic, and they are harmful even at the very slightest concentration, which is why they must stay at 0 in any fish tank. Nitrate on the other hand is harmless at low concentration, but it will weaken fish’s immune system when there is very high concentration.

Most of the beneficial bacteria colonize only in the surface areas, such as the substrate, decorations, etc. However, the filter media has the most surface areas in a fish tank, and it is where majority of the good bacteria grow on.

The process of “growing” enough good bacteria in the fish tank is what we refer to as “cycle a fish tank”, or “aquarium cycling”.

Part III – What do I need in order to fishless cycle an aquarium?

In order to cycle a fish tank, you need the following:
1. A fish tank of proper size,
2. An aquarium filter,
3. A heater if you will have tropical fish or if you want the cycle process to go faster,
4. One or two air stones, connected to a working air pump,
5. Water conditioner,
6. A liquid water test kit (I will explain it later) and
7. A constant source of ammonia (I will explain it later)

I recommend you get a minimum size of a 5-gallon tank even for a single Betta. However, a 10-gallon is better because it is only around $13~14 (a 5-gallon tank is around $11), which means it doubles in size for slightly more cost. Also, more water means more stable water chemistry and temperature.

For a filter, I recommend AquaClear power filters for small tanks of up to 30 gallons.

For medium to large tanks, Canister Filters are the better choices. They are more efficient than hanging on the back power filters in biological filtration, and they make no noise if the noise is an issue to you. However they come at higher prices.
I personally use an EHEIM Classic 2213 Canister Filter for my 40-gallon tank, and I am very pleased with it. It is a high quality German brand.



For an aquarium heater, regardless of what people say or how the manufacturer’s rated tank size on the heater, a 50w heater can be efficient enough for up to 40 gallon water or even more if you have good water flow near the heater. After I replaced my 100W EHEIM Jagar heater with a Rena SmartHeater 50W, there has been no temperature fluctuation at all. (I replaced EHEIM Jagar because it was too shining for my tank’s black background, not because it was not good).

My new 40 gallon tank during fishless nitrogen cycle
The above photo is my own 40 gallon planted tropical aquarium during fishless cycle. As you can see, basically you need to set up your tank exactly the way as it is ready for the fish. Make sure you use a water conditioner to neutralize the chlorine in the tap water before you add it to your tank. Chlorine can kill the bacteria.
You can use any type of water conditioner. I have used Kordon NovAqua+, Tetra AquaSafe, Seachem Prime, and Hikari Ultimate for my fish tanks.

While they are all good, I recommend Prime for new tanks because it can detoxify ammonia and turn it into a harmless form – ammonium, up to 48 hours.


The whole aquarium cycling process can take up to 6~8 weeks to mature a new fish tank. To grow these bacteria, a constant source of ammonia is needed. Traditionally, people use a few hardy, “expandable” fish as the source of ammonia to cycle their tanks. Most of these “expandable” fish usually will not live through the nitrogen cycle.
Lately, people see the aquarium nitrogen cycle with live fish as cruel. Therefore, more and more people now do fishless cycle. As simple as the term suggests, a “fishless cycle” is to do a nitrogen cycle without any live fish.

Some people use fish food or a piece of raw fish meat or shrimp as a source of ammonia. While this can work, I do not recommend it because it will not only make a mess in your tank with unpleasant smell, but the whole fishless cycle process will also be slowed down because you have added another procedure – waiting for the fish food or the fish and shrimp to slowly break down to produce ammonia. It can add a few more weeks to the already slow process of fishless cycling. In addition, you have no control over the amount of ammonia produced in your tank.

The more efficient way to do fishless cycle is the direct use of pure ammonia. What I did was that I bought a bottle of Ace Ammonia Janitorial Strength Formula from Ace Hardware. It is 10% ammonia and 90% water with nothing else in it. It is very important that it must have nothing else but ammonia and water in it! A good alternative product specifically made for fishless cycle is Ammonium Chloride Solution by Dr Tim’s Aquatics.



Now, what else do you need? A liquid water test kit with the ability to test ammonia, nitrite, nitrate, as well as PH! It is important to know that most paper strip test kits are not accurate and they are pretty much worthless for fish tank cycling. That is why a liquid test kit is needed. I used API Freshwater Master Test Kit.

For Saltwater tanks, you must use a different kit called API Saltwater Master Test Kit.

Part IV – Steps of doing fishless cycling

The first stage of fishless cycle

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The procedure of doing a fishless cycle is really straight forward. Start with having your fish tank set up and running, especially the filter, because it is where most of the good bacteria will grow on.
You need to put only a few drops of pure ammonia into the fish tank water. Use the test kit to check the concentration. You can do with 2~3ppm (part per million) if you plan to add only a few fish at a time. If you plan to add full stock at once, 5~6ppm ammonia concentration is needed.

A little note to everyone who might be thinking “how should I get the ammonia concentration mentioned above?” We are not doing some kind of medical procedure here, nor running a lab. :P In a fishless cycle, we risk nothing. There is no need to get the absolute precision on ammonia concentration during a fishless cycle. All you need to do is to start small, drop only a few drops of pure ammonia into the tank, then take a measurement. If it measured at 1ppm, and you want 5ppm, then do another 4x dose. It is that simple. No need to be scared of adding too little or a little too much. As long as it is not over 8ppm or higher, the fishless cycle will proceed without interference. At higher than 8ppm ammonia, the fishless cycle might be stalled due to it is too toxic even for the bacteria. If somehow you overdosed a lot ammonia by accident, and the reading is off the scale, all you need to do is to do a partial water change to lower the ammonia concentration back to 5~6ppm. No worry there.

After adding ammonia, all you can do is to wait. You need check the water with the test kit at least once a day to make sure there is always ammonia in the water. It is very important to know that ammonia can be released into the atmosphere slowly. You might see a drop in ammonia concentration without the nitrogen cycle reaching the next stage — the appearance of nitrite!

My advice at this point is to be patient! It can take weeks before there is any nitrite at all.

The second stage of fishless cycle

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Once nitrite appears, it means the fishless cycle has entered the second stage. The group of bacteria (those feed on nitrite) will start to grow as well, as they would not start to increase in number until the nitrite appear. At this point in fishless cycle, what you should do is to continue adding ammonia on daily basis to keep ammonia concentration at your desired level, while keep testing the water twice a day (once in the morning, once in the evening) to see the changes in ammonia, nitrite, and nitrate.

The third stage of fishless cycle

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Once the nitrate starts to appear, you should keep constant watch on the PH as well. The process of forming nitrate is acidic, and the water buffer will be slowly gone. As nitrate increases, PH might drop. In my case, the PH of my water suddenly dropped from 8.0 to 5.0, because my water is quite soft with next to no buffer, PH crashed easily. It is important to know that the bacteria’s growth will slow down or even be stalled at too low PH. Partial water change to keep nitrate in check is needed at this stage. You also need to continue to add a few drops of ammonia every day to make sure the source of ammonia never stops. Do not let ammonia drop to 0 for more than a few hours.

Keep doing the above until the day your tank is able to digest all the ammonia you add daily, with no trace of both ammonia and nitrite. That is, if you add 2~3ppm OR 5~6ppm ammonia in the morning, by the time you test the water in the evening, both ammonia and nitrite are 0ppm. Then, the fishless cycle is completed! Congratulations! You may now safely add fish after some more partial water changes to keep the nitrate low. Nitrate concentration is generally safe under 40ppm, however, if you want to stay on the safer side, you can keep it under 20ppm since aiming for lower is always better.

===
The advantages of fishless cycle over cycle with fish is quite obvious.
First, you will not risk losing any fish to ammonia poisoning.
Second, you have the option to fully stock your tank at once instead of adding fish only a few at a time after you have finished fishless cycling.
===

Part V – Tips to speed up the fishless cycle

The whole fishless cycling process can take up to 6~8 weeks. There are certain tips will speed up the process.

1. Get a jump start by transferring live bacteria from existing colonies.
If you can get something from an existing well established fish tank to transfer some bacteria to your tank, you will have a jump start on your fishless cycling. Ask a friend with an established tank for something such as a part of the filter media from his/her filter, or some substrate, or a decoration. However, the best thing is to get a part of the filter media from an established filter, because that is where most bacteria are as was mentioned above. If you do that, make sure to keep the decoration, substrate, or filter media wet (Use tank water, or treated water, NOT tap water.) the whole time during the transferring process, or the bacteria will die.

Note: Old tank water has no use for transferring the bacteria. No need to get that, as it is pointless. It is also important that the old tank you get your bacteria source from must be disease free!

2. Turn up the heat
If you have a heater, turn the temperature to the high 80F range. The bacteria growth will speed up in warmer water, thus shorten the time needed for the fishless cycle.

3. More oxygen
If you have the air pump and air stone ready, turn it up! More oxygen will aid the growth of the bacteria. This step is particularly important if you did step 2 to turn up the heat. Warmer water holds less air, so you will need more oxygen in the water in order to speed up the nitrogen cycle.
If you are looking for an air pump, I suggest Rena air pumps. It is quieter compared with other brands. I use both a RENA 300 (1 outlet), and a RENA 400 (2 outlets).

4. Bacteria products
There are products on the market manufacturers claimed that they contain live bacteria to aid the cycling of the tank. Many of them are bogus, or with the wrong type of land based bacteria which will drown in the tank water after a week.

The only proven working product of the correct types of live bacteria for nitrogen cycle is Tetra SafeStart (make sure you get the name right. There are many other Tetra brand products, but only SafeStart is what you need to aid the cycle).

(Make sure you buy the bottle rated at least 2x of your tank size.)

While Tetra SafeStart can be used for cycle with fish, I have bought and tested Tetra Safe Start in two of my tanks for fishless cycle. The results were quite different though. The first bottle got a 10-gallon tank cycled instantly. After I had added 2ppm ammonia, it was all gone by the next day with no trace of ammonia or nitrite, and I had a reading of nitrate. The second bottle did not work as well as the first time in a 5.5 gallon tank, nevertheless, I got a reading of both nitrite and nitrate the very next day, which still cut a few weeks time off the whole fishless cycle process.
How the shops’ warehouse stored this product might have resulted in the different effectiveness in two different cases. These bacteria might have special needs in order to survive in a bottle.

Whether or not you choose to use a shortcut for your fishless cycle does not change the requirement that you have to be patient, and it is very important to keep a constant eye on the water chemistry with the liquid test kit! Most important of all is to keep a constant source of ammonia!

At the end of my own fishless cycle, my EHEIM canister filter in my 40-gallon fish tank was able to “digest” 5~6ppm ammonia daily. I was able to add a full stock of 30+ tropical fish at once with no problem at all. Both ammonia and nitrite stayed at 0ppm at all time.

(If you have any questions or comments on fishless cycle or aquarium nitrogen cycle in general, you are more than welcome to post a thread on our Pet Forum.

Good luck with your fishless aquarium nitrogen cycle! :D

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59 thoughts on “Aquarium Nitrogen Cycle and Fishless Cycling

  1. I have a 37 gal. tank that has been cycling for 7 weeks. The ammonia is high still (0.5) and the nitrite is slightly elevated, despite expert tips to add extra prime water conditioner and beneficial bacteria (Big All’s brand). I was informed that the high ammonia is due to high levels in tap water, so I have been reluctant to do 10-20% water removals each week as I would be introducing even higher levels of ammonia into my tank. Pet store finally recommended that I add fish as this should contribute to the cycling of the tank (bought 3 pearl danio). I am thinking to purchase the beneficial bacteria you have suggested. Is there anything else I should be doing or better way to keep ammonia levels down (better water conditioner?) ?

    • Hi, Tina,
      First, you need to test your tap water to find out whether or not there is ammonia in it.
      By the way, what is the source of your ammonia during the fishless cycle? Did you use pure ammonia or fish food or something else? It is very important for us to know in order to give you a better answer.

      Second, Prime is just a water conditioner, it does not contribute anything to the nitrogen cycle. All it does is to detoxify ammonia, and change it into ammonium, a less harmful form for up to 48 hours.

      Third, water change is not needed during the cycle until you have excessive amount of nitrate.

      Fourth, the store just wanted to sell you something. You shouldn’t have listened to them. No fish should be added if there is trace of ammonia in your tank.

      Fifth, yes I would recommend you to get Tetra SafeStart as soon as possible to speed up the cycle. Your fish are in danger as long as there is ammonia. Although Prime can protect them to a certain degree if you do partial water change with it every other day. You can speed up the cycle by applying some of the tips in the articles.

      If you have any further questions, we recommend you to post a thread under the fish section on our forum. It is much easier for back and forth conversation. :)

      Good luck!

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  3. Please help me my fish were inactive and then one of them died recently and I highly think that I need plants for my tank so please tell me are plants essential.

    • Fish don’t need plants in aquarium in order to live.
      One of your fish died and the others are inactive must be some other reasons. You need to provide more information such as your tank size, filter system, temperature, water conditioner, readings on ammonia, nitrite, nitrate, PH, as well as what species of fish and how many fish you have. Please use the Forum for questions. It only takes a minute to sign up, and it is free. Much easier for back and forth talk. ;)

  4. Im going to be cycling a new 55 gallon tank, im going to try to do all the tips you added that can speed up the process. 2 questions though. How long do you think it may take to do the fishless cycle with the starter cycle stuff, air stones, and the heat up, oh and gravel and fake plants/big rocks from my 30 gallon. And how would i ad filter media to my new tank from my old (i want my 30 gallon still up and running) can i put the new 55 gallon filter on the 30 gallon tank and vise versa to help things move along or would the 30 gallon tank suffer? Thanks for the help in advanced!!!

    • Hi Andy, there is no fixed time for any kind of aquarium cycling. Not to mention everyone’s goal is different. Even with heavy seeding and all the other tips, and your goal is only 1ppm ammonia converted daily, it can take anywhere between a day to around 2 weeks. If you run two filters along side of each other, the bio-load will be split between the two filters. Each filter will only be able to handle a part of the ammonia produced by your current fish. For further question, join our free forum to discuss. :)

  5. I recently bought a 55 gallon aquarium starter kit and a topfin 50-75 gallon aquarium stand for this tank. After a day of putting the stand together with minor complications the stand seems a but wobble-y…? Will the weight of the tank with water even it out the stand? Is it normal for a fish tank stand with no tank of top of it to be a bit wobble-y? Thanks SOO much in advance!

    • Andy, this is an article about fishless cycle. If you have question or comment other than for this article, please use our forum. It is free and only takes a minute to sign up.

  6. I’m starting to lose hope for my current fishless cycle its been nearly 3 weeks and my ammonia still hasn’t dropped yet. It’s still at 4ppm and my nitrite is at .50ppm and not much has changed. Should I do a water change?

    • Be patient. It is perfectly normal to take 3~4 weeks just to start to see nitrite to show. You do not need to do water change at all at this stage as the article stated. The water change is only needed after nitrate start to build up which can cause PH drop if you don’t do it.

    • You do not need lights for fishless cycle. It helps nothing. Most aquatic nitrogen bacteria colonize the filter media anyway, which is away from the lights unless you have a sponge filter. Having lights during fishless cycle might cause an algae boom. So you should keep the tank as dark as possible.

  7. Hi, i have a question re the filter during a cycle …..On the instructions for my large size filter it says to change the cartridge once a month…but a fishless cycle takes 4-6 weeks…Sooo when exactly do i change the filter cartridge while/after doing a cycle ??? thx so Much!!!

    ~Frank

    • Do not change filter cartridge until it falls apart. The only thing needs to be changed is activated carbon pad. Activated carbon is really not needed anyway unless you try to remove medication in the water. If you replace other cartridge, you remove beneficial bacteria, thus you crash the cycle even if the tank is already established. For further questions, please ask them on the forum.

  8. Hello.

    I have a 20 gallon tank I have been cycling for around 2 months now. I started seeing nitrates about 7 weeks ago. Around that time, the nitrates and nitrates were off the chart. The last 2 weeks, my water levels have remained almost the same.

    High Range pH: fluctuating from 8.0 to 8.2
    Ammonia: fluctuating from 0.25 to 1.0
    Nitrates: 5.0
    Nitrites: 2.0

    These are the latest test results I got. I’m adding ammonia when the ammonia drops below 1.0ppm. I read in your article that ammonia should be added a few drops everyday. Is this what I am doing wrong? It’s been a really long time and I think I am just losing my patience. I used API Stress Coat and Stress Zyme earlier in the cycle. I did a partial water change once about 2 weeks ago. I had no means of getting a filter from an established tank. Any advice would be greatly appreciated.

    • Come to join the forum and make a new thread about your fishless cycling problems in the fish section. It is easier for us to help you there. :)

  9. i dispute the usefulness of fishless cycling. please tell me, how exactly can you know when to add fish…yes, i know…when ammonia and nitrite are both zero, BUT…if you’re adding ammonia DAILY, there is going to be a “window” of, maybe a few minutes, an hour…who knows? if you don’t add fish at EXACTLY the right time, they will be going into ammonia or nitrite, or a dead filter system.
    kindest regards,
    steve

    • I really do not see your point. Your argument is based your belief that bacteria can die quickly without ammonia, which is false. The beneficial bacteria in the filter does not need to be fed every hour like you think. Their usefulness can last for a few days without any source of ammonia. Dr. Tim the guy who invented Tetra SafeStart even suggested these bacteria do not need to be fed every day. I personally wouldn’t go beyond 24 hours, although 24 hours is just the time to “start expiring” instead of “all expired”. After the tank is cycled, you have a 24-hour window to add fish while the bacteria are still at 100% efficiency without the need to add more ammonia. In other words, no need to add any more ammonia if you know you are able to add fish within the next day. Isn’t that extremely easy to do? I ordered my fish online, and even I was able to time it perfectly. Worst case scenario (even if) you somehow accidentally dumped ammonia into the tank again when it is no longer necessary, just don’t go get fish until the water test results come out at 0ppm for ammonia and nitrite. How hard is that?

  10. Too many hocus focus. just add fish, dechlorinator, good amount of aquarium blue salt, heater for tropical, good filter, aeration, put some old filter if you have add some water from old aquarium. VIOLA~~~

    • Why would you put salt into a freshwater aquarium? It is not needed unless you are trying to kill some parasites. Old water isn’t going to help aquarium nitrogen cycle because all the good bacteria for converting ammonia and nitrite are surface based. You will find next to 0 of them in the water “free swimming”. Yes, old (still running) filter will help since it is already cycled. Ammonia poisoning is a very real threat to the fish in all new aquariums. If you just add fish like that without an already cycled filter, they will suffer permanent damage even if they survive through the cycling.

  11. I noticed that you didn’t mention anything about diatoms. From the research I’ve soon it suggest that diatoms form at the end of the nitrogen cycle and are part of the process?

    • Diatom is brown algae. Algae growth requires lights. There is no reason to keep your lights on during a fishless cycle unless you have plants. In my planted aquarium, I had no algae at all until a few months after I added fish.

  12. I’m doing a combination of pure ammonia and live rock fishless cycle for my aquarium. I light my aquarium because of the live rock I have. I would rather have my diatom/algae bloom now during the cycle than later when I have fish

    • So you are having a saltwater aquarium. Be careful with your live rocks during fishless cycle. You might kill off your live rocks with the toxic ammonia.

  13. hi, your artical was really helpful and I wanted to ask you can the objects (which have good bacteria on them which you transfer from a cycled tank to a cycling tank) be plants?

    • Plants don’t hold much bacteria on them. The bacteria are surface based, so you need to find something with lot of surface areas. As it was mentioned in the article, a piece of filter media is the best “object” for bacteria transferring. Some gravel is the next best thing. Other objects such as driftwood and other decoration aren’t as useful but will help to some degree. If you can’t get your hands on these things, it is the best to get one of those live bacteria products. Tetra SafeStart is very very helpful in jumping start your cycle, and it is also in the article. :)

    • Plants will of course have some bacteria growing on them, but the bigger issue with having them in the tank during the cycling process is that the plants themselves actually consume some ammonia, nitrite, and nitrate. This isn’t a huge problem, but with a sufficient amount of plants the cycle can actually be stalled somewhat since the plants are competing with the bacteria (which are working doubly hard to establish themselves).

      • Not quite accurate. While plants do consume some ammonia and nitrate, the amount of intake is puny. You’d have to cover every square inch of a 30 gallon fish tank just to take care of the ammonia produced by two tiny Neon Tetra. So the plants are irrelevant here. On the other hand, the transfer of plants from a well established aquarium will not give significant boost to the bacteria in the new aquarium. After all, plants do not have a lot of surface areas to host these good bacteria.
        P.S. I did complete my fishless cycle with full tank of plants. My aquarium was able to convert 6ppm of ammonia daily. While the impact of plants is insignificant, it is also irrelevant what(the bacteria in the filter, or the plants) consumed the ammonia. As long as 6ppm of ammonia is gone daily from my aquarium with no trace of nitrite either, the aquarium is ready for adding fish. :)

  14. Help. I recently Brought a Marina 5 style Fish tank 2 years ago. I started out with tropical fish, and I brought all the equipment the store clerk told me to, such as (temperature, nitrogen Cycle, aqua Plus cycle and pH and ammonia test kits). a year later I realized that my fish were gasping for air at the surface of the tank and I always do weekly water changes. then suddenly they died. This year I decided to try again with Gold fish and I brought a few new equipment. I brought an air pump and a new slim S10 filter. I have allowed the tank to go through the chlorine and nitrogen stage using the nitrogen cycle and the Aqua Plus Cycle. I am worried about the ammonia and pH levels of my tank, I can’t get an accurate reading, it shows 0.5 for pH and 2.0 for ammonia. What should I do. I want to let my Gold fish live as long as me.

    • oh I forgot about the temperatures, for the tropical fish I had the temperature set to 26 degree Celsius with normal. with light it is 32 degree Celsius. The marina light is not well use for this tank since it quickly heats the tank. for the gold fish, the temperature is 24 degree Celsius, I can’t use aquarium light since it make them uncomfortable.

      • Hi Alex, could you please post your question in details on the forum as a new thread under the fish section? It is easier to answer your question there. Thank you!

  15. I notice above about plants not holding a large enough surface area to hold the beneficial bacteria. Although the plant in itself is not a key to speeding up the process. Often, I have found the rock wool that they are planted in to be hugely beneficial on a potted plant. Providing that the plants are from a healthy tank then the bacteria will grow on the rock wool. Not as good as gravel or filter media. But a worthy addition nonetheless

    • Anywhere from 2 to 6ppm ammonia. If your plan comes with heavy stocking of fish, then make it closer to 6ppm. If you have any more questions, you are welcomed to use our forum. :)

  16. Great article!! Ive been cycling now for a week and im worried ive run into a problem. I added too much ammonia on Day 1 and tried a 50% water change to dilute it. It still appeared off the chart so i decided to leave it. After 2 days my nitrites read off the charts (by the way im using the API Master kit) i waited a few days and did a 90% water change in fear that my tank was stalling. Now its been a week and as of now my ammonia reads at about a 2-3 (just added it about an hour ago), my nitrites are still unreadable, and my nitrates and very low, in about the 20 range. My pH appears steady at an 8. Would Tetra SafeStart help get rid of some of these nitrites? I really dont want to do another water change and harm any bacteria trying to trive at this point unless you feel its a must!

    • Water change should not harm your beneficial bacteria, as long as you do not use untreated tap water nor wash the filter media unnecessarily. Since you have already had nitrite and nitrate readings, using Tetra SafeStart during this stage is not needed. TSS is a form of heavy bacteria seeding for jump (start) the cycling. There is no need for it after your fishless cycling had already (started). :) You should not add more than 6ppm ammonia, and the off the chart nitrite reading is perfectly normal (I have been there). Just don’t let the PH start to crash, and you are doing just fine.

      • Hey I have a 36 gallon tank and I plan on using it for cichlids. I have no access to seeds and I was wondering what that tetra safe start would do to my tank. I don’t exactly have the funds to purchase all of my cichlids at one time yet, and I was wondering after I used the TSS how could I keep the bacteria alive? Do I just keep adding ammonia to keep it alive or should I just wait it out? Any advise is much appreciated!!!!!!!!!!!

        • Hello Cichlid lover,
          Tetra SafeStart is designed for adding fish (in small batch) soon (usually 24 hours later) after you have used it in your tank. If you can’t get fish soon after using TSS, or if you plan to get full stock of fish at once, it is recommended to use a source of ammonia to keep the live bacteria fed. The live bacteria will die out completely in less than a week if there is no ammonia for them to feed on. A source of ammonia will also help the good bacteria seeded by TSS multiply in number… since it is unlikely a bottle of TSS will give you enough live bacteria to convert all of the ammonia produced by a tank full of ciclids from day one. You’d rather have more than enough bacteria before you add the fish than taking chances of give your new fish some degree of ammonia burn. :) If you are unclear about certain answers or if you still have more questions, feel free to use our forum where we can chat.

  17. I’ve been fishless cycling my tank for 1 month already. The ammonia was dropping because the nitrite and nitrate were now present. I added ammonia everyday. Everything was going fine until two day ago. The ammonia has stopped dropping. What happened? My ph level was fine too.

    • Hello Frank, without further information it is very hard to determine what the problem is (if) there is a problem at all. If you make a thread on our forum under the fish section with all the details of how have you been doing your fishless cycling, we will be gladly to help you. :)

      • My ph and KH were too low so I put baking soda to raise them up. Two days later, my ammonia is still the same but my nitrites and nitrates are going down. It was stalled for about 4 days before I did anything. Did my fishless cycle restart? If so, do I have to change the water and redo everything?

    • Hi Saikat, there is no fixed timing for fishless cycling. It can be longer or shorter depend on many factors such as water temperature, filter efficiency, availability of the ammonia, water PH, etc. On the average in most cases, it takes around 6 weeks (if without) using heavy bacteria seeding at the beginning. As we have gone through in the article, heavy seeding from the start can shorten the time greatly. Fish tank size has no effect on the time required for the cycle. You are cycling the filter media basically since most beneficial bacteria will be colonizing there. If you have more questions, please use our forum to ask.

  18. Hello ,I have recently installed a 100 liters fish tank and put 5 black tetras,2 tinfoil barbs,2 gold fish in it please tell now how do i complete the nitrogen cycle in this new tank with these existing fishes.A water filter ,air pump & heater is also installed in it.How many days it will take to complete the cycle?Shall i change the water during the cycle if it seems milky?can medicines like anti itch ,anti chlorine may use during the cycling process?
    Thanks for your valuable advise in advance………

    • Hello Nitin Kumar,
      Since you have already added fish to your aquarium before you have run a nitrogen cycle, now you can no longer do “fishless” cycle. Your only opinion is “fish-in” cycle. It requires much more constant partial water change, and some of your fish might die to ammonia poisoning before the cycle is done. Do (not) use any medication for no reason at all. They will only harm your fish. I would suggest you to get SeaChem Prime and Tetra SafeStart as soon as possible. Both were mentioned in the article. Prime can detoxify ammonia for up to 48 hours, which is useful for minimizing the damage your fish receive from ammonia burn. Just keep up with the partial water change and use Prime for the new water every time. Tetra SafeStart can be used to heavily seed the beneficial bacterial to jump start and speed up the cycling. If you have any further question, please use our forum. :)

  19. I have a 55 gallon aquarium I set up. I’m doing the no fish cycle. I have been up and running now for about three weeks now. I am right on the money with everything but imiona. I have been bring water samples to my pet shop which I see they usr paper and I read you use the liquid form for better accuracy. I had been told it was stressed and to do a 30 percent water change. I have used terra safe start. And the imiona is still high in the stress I was told.I am using a whisper filter 60 dual sided with bio bags and sponge. I have a bubbler going on high speed and a 200 watts heater which was set at 75 but was told to turn it up to 80 for the time being. This is going to be a community tank and I’m stressed don’t know what to do…..why is imiona still in it. I was told that this should be done in a week or two by the pet shop but I read it can take up to 8 weeks am I on the right Track or did I screw up. I don’t want to harm my fish when I can get them but for now I am fishless…..please help.Thanks….

    • @ Casper,
      You do not need to do partial water change when you have no fish in your tank during fish(less) cycle.
      It is your goal to grow enough beneficial bacteria in your filter media. To achieve that, you need the ammonia in your tank as a food source for the good bacteria. If you have more questions, please ask it on our forum.

  20. I have a 150 gallon tank that I just finished switching from saltwater to freshwater (I scrubbed and rinsed everything out: the filter, bio balls, and all of the hoses.) I just turned on the filter today. I’m going to order the SafeStart as soon as possible but I was wondering: should I pour it straight into the tank, over the bio balls, or into the filter? Any advise you’d like to add other than answering the question would be greatly appreciated, thank you!
    PS: A person at my local fish shop said if I got a few cycling fish ( I forgot their name, but I rember him saying that they’re the damzels of freshwater fish) that will help establish the tank in a week or so.

    • Hi Mohamed,
      Just dump the whole bottle of Tetra SafeStart into the tank while the filter is running. The filter will go through all of the tank water anyway. So it doesn’t matter. You need to make sure there is a source of ammonia. We recommended pure ammonia products for fishless cycling. However, it can be done with hardy fish too (example: Zebra Danio) but not recommended really. Without heavy bacteria seeding from TSS, it is impossible to cycle your tank in a week or even a month with or without fish. You should expect anywhere from 6~8 weeks for normal cycling without jump start from TSS.

  21. Hello,
    I am doing a fishless cycle for my 20 gal fresh water tank. I used Dr. Tim’s One and Only nitrifying bacteria and his ammonia to start the cycle. I am on day 7 into the cycle and my API freshwater Master test kit reads….. Ammonia
    .50ppm, Nitrite 5.0ppm and Nitrate 20ppm. My question is…. do I wait till I get a 0ppm reading of both ammonia and nitrite before adding more ammonia? Or do I add more ammonia when just the ammonia reading is 0ppm. I know that my nitrites are high and I don’t want to make it worse by adding more ammonia to soon. Or does it matter? Also when I add more ammonia do I dose it 20 drops again (1 drop per gallon) like Dr. Tim’s recommends at the beginning of the cycle? That brought it to a 2.0 ppm reading when I started.
    My nitrites have been at this 5.0 ppm level for 3 days now but my ammonia has been dropping slowly. Any advise would be greatly appreciated. Thanks!

    • Hi Lorraine Smith,
      You need to add ammonia when the ammonia reading is down to 0ppm. Otherwise the bacteria feeding on the ammonia will be out of food and stop multiplying. :P

      Nitrite at 5.0ppm is high (high enough to kill the fish really fast), but it is nothing for a fish(less) cycle. So do not worry about it. As your nitrate reading is going up, it means the nitrite is being fed upon by nitrite eating bacteria. It is a great sign!

      If you want to finish the fishless cycle as quick as you can, it is the best to keep both types of bacteria well fed at all time.

      If you have any further questions, please ask it on our forum. :)

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