Cycling Methods & Procedures


All Gr8KarmaSF's fault....
Original poster
MFK Member
Apr 2, 2007
Staffordshire UK
Cycling a Marine Saltwater Aquarium

Article written by Reefscape and Yash

Since many have asked questions on the cycling process and the things it entails, we thought we’d put together some sort of a guideline that you could follow. Please note that this we have placed more emphasis on the fishless method, as we personally prefer not to put any livestock (as hardy as they might be) through the stress and damage that the cycling process can cause them.​

Fishless Cycling

Firstly, if possible, you do need to start off with something that might have some bacteria on it. You could use a little piece of live rock, or a cup of two of sand from an established tank, or some bioballs or medium from an existing filter. You need something that has life on it to seed the sand and rock. Even if you only manage to get hold of a few pounds of live rock and cup or two of live sand put on your existing sand, it will start the growth process off for you, because if everything is in effect dead (sand and rock) it will take a really long time to get the living organisms to take hold​

Once you have your tank ready for cycling, there’s three ways you could go about doing that:​

Method 1:

You could add a medium sized raw prawn/shrimp to the tank and wait for it to start rotting (it probably take it 2 days or so). A little piece of friendly advice – put the prawn in some pantyhose and then stick it in the tank as once the prawn decomposes, it’ll pretty much disintegrate and create a big mess in your tank when you need to take it out. The raw shrimp/prawn should only be placed onto the substrate or suspended in the water and not onto the rock. The reason behind this is because when the decomposition starts, you don’t want to have ammonia seeping into the porous rock as this could lead to ammonia spikes at any time when it eventually gets released back in to the water. When the prawn decomposes, it will create ammonia (NH3), which you should be able to see rise on your daily tests. The NH3 will eventually spike, which causes nitrITE bacteria to be generated, which in turn will control the ammonia and reduce it down to zero eventually. When this happens, your nitrITE (NO2) will start to rise to a peak, and again, you will now start to see this on your daily tests. The same process now happens with the nitrATE (NO3) bacteria this time. They feed off the nitrITE, which gets turned into nitrATE, and when a sufficient amount of nitrATE bacteria have been grown, they reduced the nitrITE down to effectively zero. Your nitrATE should now rise from zero anywhere up to 10ppm or even 15-20ppm. Once you see that ammonia and nitrITE have checked out at 0ppm over a few days, it’s fairly safe to assume that your tank is cycled. A good way to test this is by using PURE ammonia to dose your tank. This is not an absolutely necessary step but you can do it just to double check. Use only pure ammonia as I have listed in Method 2. You will need to add a few drops of the NH3 so that the NH3 levels in your tank get bumped up to maybe 1ppm. Test your water in 12-24 hours and see if either any ammonia or nitrites show up. If neither shows up, your tank is cycled. Once your tank cycle is complete, you will need to do a fairly large water change (~ 50%) to bring the nitrATES down. Just a warning about using this method: the decomposing prawn may cause a pretty bad stench (it did in my case) – so make sure the room that the tank is in has plenty of open windows/air circulation.​

Method 2:

Instead of using the prawn to create the ammonia spike, you can simply start off with pure ammonia. A very important thing to remember here is that you have to use PURE ammonia only – one without any additives or perfumes in it. The household cleaning stuff is perfect for this use, but make absolutely sure that it does not contain any additives or perfumes before using it! It should be free of surfactants, perfumes, and colorants. Always read the ingredients on the bottle. If it doesn't list the ingredients or say Clear Ammonia (or Pure Ammonia or 100% Ammonia, or Pure Ammonium Hydroxide), then leave it on the shelf and look elsewhere. Shake the bottle if you're not sure about it because Ammonia with additives will foam, while "good" Ammonia will not.
Different brands of ammonia might come in different concentrations. Also, the size of your tank will also play a factor in how much ammonia you would need to use. So, in essence, there is not hard and fast rule about how much (how many drops or spoons/gallon) you would need. You’d be best of starting really slow until you figure out how much you need to doze your tank moderately. I say moderately because you really don’t want to jack up the ammonia in your tank to such a high level that the life in and on your rocks/sand gets nuked. The method I have listed below uses ammonia with an approximate concentration of 28%.​

You can start off by adding X drops amount of NH3 until a level of 5ppm is achieved. This X amount of drops has to be added daily until the nitrITES spike. When the nitrITES spike dose the tank with ½ X (from previous step) amount of NH3 drops daily until nitrITE is 0ppm causing a nitrATE peak. Once again, once both NH3 and NO2 have checked out at 0ppm over several days, and your tank is cycled, do a large water change to reduce the NO3. I personally don’t like this method a whole lot since it stresses out the tank a fair bit.​

Method 3:

This is basically the same as Method 1. Instead of using a prawn, you can simply add fish food to the tank, and let it decompose, creating the NH3. This might take considerably longer, and you might be left with lots of decaying food in the tank.​

Please keep in mind that using any of the above three method creates only a certain amount of bacteria colonies capable of handling a limited amount of ammonia. So, once the cycling has been completed always start to stock slowly, as rushing things might cause another ammonia spike, which is not good for the livestock you will have in the tank. When you start stocking your tanks, it is advisable to start off by adding one fish and leaving it in the tank for two or three weeks before adding any more fish. This gives the bacteria time to reproduce enough to a level that it can handle the toxic waist that is produced by that one fish or excess fish food that you have not managed to remove after feeding.​

Fishy Cycling

This briefly describes how you can cycle your tank using a fish, if you must.​

Method 4:

This method involves using a very hardy fish to cycle the tank from the start of the cycle. There are so many people out there who run out as soon as their tank is filled and go and buy a Damsel or some other very hardy fish. Yes, this will start the cycle off because you are introducing ammonia into the ecosystem via the living fish. BUT, there are a few things that people should be aware of about this method.​

1. It is very inhumane to put any living organism through the cycling process, as there is a very good chance that the fish will not survive. The ecosystem cannot really support a fish yet and the toxic waste will effectively burn the gills of the fish that is being used.​

2. IF the fish survives the cycling process…now what??? You have two choices: Leave it in there because it now has taken over the entire tank as its territory and there is a good chance that it attack and possibly kill any more inhabitants that you introduce to the tank. The second option is to try and catch the little possessed monster. And trying to catch a fish in a tank that has equipment in there and live rock, with nooks and crevices in it, is near on impossible. Lets face it, you have put him through all the pain of the cycling and now he thinks it’s his God given right to own the tank.​

As you can all imagine, method 4 should be banished as its very inhumane, but still people prefer to use it.​

Method 1 would give you the best results as you are using nature, and letting nature take its own course without being forced, has to be the way ahead. None of us out there want to rush our new fish tanks as we have all spent a lot on money and resources on them and want to end up with either beautiful fish only system, or that gorgeous Reef.

ReefScape / Yash​


Feeder Fish
MFK Member
Mar 10, 2007
very well written Mr Reef!! lol. The method i use is buying either CURED LR or UNCURED LR and letting that do the work. Uncured is best because you dont have to let the rock dry out to cause any die off but it does work either way.


Feeder Fish
MFK Member
Jan 1, 2008
Morris, IL.
It looks like I am going to get my 375 gallon tank started up within the next month or so and I am thinking of doing the pure ammonia method. I will have no live sand or rock in it at first. My question is, can it be cycled in 3 weeks, 4 weeks, 5 weeks. Does this speed up the cycle time this way?

Venom SS

Jack Dempsey
MFK Member
Aug 14, 2008
Deano1956;2927307; said:
It looks like I am going to get my 375 gallon tank started up within the next month or so and I am thinking of doing the pure ammonia method. I will have no live sand or rock in it at first. My question is, can it be cycled in 3 weeks, 4 weeks, 5 weeks. Does this speed up the cycle time this way?
Im using the pure ammonia method as we speak on a freshwater 350g. I added the ammonia about 3 weeks ago. It took about 2 weeks for the ammonia to go from 5 ppm to zero. Now of course my nitrites are sky high, so what im doing is bumping the ammonia back up to around 1-2ppm every time it reaches zero, Just to keep the ammonia eating bacteria alive. I have to add ammonia about every 24hrs. Now its just a waiting game for the nitrites to start to come down. I would think they should start to drop sometime next week. If that is the case, then it will have taken approx. 5 weeks to cycle. As high as the nitrites will be though due to all the ammonia getting eaten, I really expect it to be more like week 6 before its ready.

Im running the tank at 84 degrees and I also "seeded" the tank after I got the ammonia to 5 ppm. I just took 2 of the 4 sponges from one of my established canister filters and basically cleaned them in my sump. Submerged them in it and squeezed all the gunk out. I think it helped quite a bit.


Feeder Fish
MFK Member
Mar 29, 2010
i used a bunch of live rock and live sand to start my tank off and it cycled very fast. it seems like the easiest way to do it


Feeder Fish
MFK Member
Jan 4, 2010
What would you guys suggest I do to cycle out my 90 gallon that is coming on thursday? I am looking for the quickest option for me.


Feeder Fish
MFK Member
Apr 3, 2009
The Redwood Reef
Use Seachem's Stability:

"Stability® will rapidly and safely establish the aquarium biofilter in freshwater and marine systems, thereby preventing the #1 cause of fish death: "new tank syndrome". Stability® is formulated specifically for the aquarium and contains a synergistic blend of aerobic, anaerobic, and facultative bacteria which facilitate the breakdown of waste organics, ammonia, nitrite and nitrate. Unlike competing products, the bacteria employed by Stability® are non-sulfur fixing and will not produce toxic hydrogen sulfide. Stability® is completely harmless to all aquatic organisms as well as aquatic plants, thus there is no danger of over use. Stability® is the culmination of nearly a decade of research and development and represents the current state of the art in natural biological management.

Sizes: 50 mL, 100 mL, 250 mL, 500 mL, 2 L, 4 L, 20 L

Why It's Different
Illustration of Stability's™ bacteria on biofiltration material. stability contains a synergistic blend of aerobic, anaerobic, and facultative bacteria
The bacteria used in competing products are inherently unstable. The conditions necessary for their growth and development fall into a very narrow range of temperatures, pH, organic loads, etc. When any of these parameters are not strictly within the proper range, the bacterial culture quickly crashes and dies. Stability® does not contain any of the aforementioned bacteria.

The bacteria strains in Stability® have been in development for over a decade. The necessary conditions for growth of our bacterial strains encompass a very broad range. When other bacteria begin to die off (usually from high organic loads caused by the undetected death of an organism), Stability® simply works harder and grows faster! The strains function in fresh or saltwater. Stability® contains both nitrifying and denitrifying bacteria, a blend found in no other product. Additionally, Stability® contains facultative bacterial strains which are able to adapt to either aerobic or anaerobic conditions. The bacteria in Stability® are non-sulfur fixing, another innovation in the industry. Most other bacterial supplements will form toxic hydrogen sulfide under the proper conditions. Stability® will not, ever."

I use this for my QT whenever I want to bring it up for new fish. Works great, no need to transfer sponges, live rock, sand, etc. Just add the new fish, add Stability as directed....Done!


Feeder Fish
MFK Member
May 14, 2005
tyndall72;4025501; said:
What would you guys suggest I do to cycle out my 90 gallon that is coming on thursday? I am looking for the quickest option for me.
The quickest option is to cycle the tank water artificially with an ammonia solution. It's okay to use commercially-available bacteria colony starters, but there is no short cut to the amount of time required to grow a biofilter bacterial colony robust enough enough to handle a regular livestock load.

Nitrosomonas are nitrifying bacteria that mature to colony strength at about 10-14 days on an increasing ammonia load. Daily ammonia tests at that time should begin to approach zero ppm.

In another 7-10 days, Nitrobacter should grow to full colony strength. Nitrite readings should be zero ppm, with nitrates rising quickly.

On your third week, abruptly stop adding your ammonia solution load, do a 50-70% water change, and add all your desired fish livestock all at once.

Take care not to raise your bacteria-loaded biofilter out of the water. Keep it undisturbed as best you can so as not to dislodge your hardworking bacterial colony from the filter material. The worst thing you might do is to expose your biofilter to the air, thereby decimating more than half your painstakingly-grown colonies.

That's 3 weeks to cycle a tank properly. That's the quickest way.
Otherwise, you'll get dead fish.

Good luck.