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Cycling Methods & Procedures


Trance Addict
Cycling a Marine Saltwater Aquarium

Before all else, a ton of credit goes out to Reefscape, who I collaborated with on this sticky, for helping out with additional matter, suggestions, comments and editing.

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 that you call “My Part of the Ocean”
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I shoot people with a Canon
Staff member
What do you mean "speed cyclers"? If your refering to the additives that you put in your tank to get a super quick cycle, then yes, you could use them..

How-ever, the whole point of cycling a marine aquarium is to let nature do its work, under its own steam. Why rush something that is potentially gonna last you for years and years to come??

All the methods that myself and Yash have gone through in this sticky all use mother nature and take advantage of how nature can take a hold in a tank.

It is, by no means, an exhaustive list of methods to cycling a tank, it is mearly a list of what we suggest you use. It is entirly down to the individual how they choose to do it...



Trance Addict
Niko is spot on there in his comments. In my own opinion though, additives that are supposed to speed up the cycle rarely work. Its just a waste of time and money IMHO. I'm always of the notion "don't mess with nature ... cos it will end up biting you back" Let it take its course and all will be happy :) That's why my favorite method out of those listed above is the raw prawn method ... a natural form of ammonia, creating natural bacterial colonies, resulting in a tank cycled by nature itself rather than some additive!



LOOK! it's a fish........
ok, when cycling a new tank using any method, is it best to leave things like protein skimmers and other filters turned off? unless of course there is media inside that you are trying to cycle.

I am setting up a new tank for some friends, but I have never done SW, I like the prawn and pantyhose idea though.

but, from what I understand, a protein skimmer would slow things down, so just leave a couple power heads running for circulation, and wait for the sand/rock to cycle, right?


I shoot people with a Canon
Staff member
personally, i would not run the skimmer, but you may as well make use of the filter, with its media, as it will filter out the die off from the rock.

want you want is to have the tank running as it should do, with water circulation, as though there were fish in it. That way, its done then, all you have to do then, when the cycle is complete is power on the lights and skimmer and away you go...

Protein skimmer wont exactly slow the cycle down, i just dont see any benefit of running it while its just cycling...

Like i say, some people have it running from day one..It boils down to personaly preference really...



I shoot people with a Canon
Staff member
I would not use a filter from a freshwater system, no. Different paracites and bacteria are there in freshwater systems than in marine. I dont think its worth the risk of something getting introduced into the system...



Salt-aholic Xtreme
DO NOT ATTEMPT TO CYCLE YOUR TANK IN ANY LESS THAN A FEW WEEKS!!!!!!!!! The cycle lays the foundation for a tank, if you do not have the patience to do it right then you really don't have the patience to have a marine tank let alone a reef. Not to mention that Cycle is a freshwater & saltwater product, This tells us right away that it is a garbage snake oil producty as the bacteria in a marine and freshwater tank are compleatly different. Stress Zyme does nothin for the cycle it only helps to build the fishes slime coat, AND causes your skimmer to go nuts which is not really what you want as by the time you add fish you want your skimmer broke in and running at it's prime.

Not to mention that all this CRAP costs money that could be put to much better use on equipment and additives that first of all work and second of all arn't a money scheam.




AC Members
I was quite lucky, being about my 4th tank cycle, I decided to use a new method. I ordered 60KG of live rock from my LFS, they sell it in bulk it is air expressed from Cairns, and you pick it up from the airport. It is significantly cheaper to do it this way, but you don't really know what your going to get. They come in Styrofoam box's with "life fish" written all over it. When I got it home and open the box's the rock was in thick plastic bags with salt water in it. No Smell, apart from the ocean (this stuff didn't look like it had been hauled from then end of a boat ramp) It went straight into the aquarium on top of about 4" of aragonite, I was amazed at the amount of pistol shrimp, brittle stars and a whole bunch of bonus corals, sponges, and amazing types of macro algae. This went straight into fully lighted system, an arcadia pendant with 2x250 watt MH's, no ammonia spike, one week later mark arrived, my yellow tang, and about 4 years later he is still the star, 4 tank moves as well. The best thing I found was the amount of uptake of critters directly into the sand bed, and I still have the same sand, and I can just sit there and watch the array of creatures that have made it there home. The guy at the LFS said I was the only person he knew that was so fanatic about this process, and said some how, once it ends up in the dealers tank, no light, just dark, everything just seems to die. I quite often buy coral which has been left for dead, at live rock price (because that is where it ends up) and get it going again, sometimes they live, sometimes they die, but hey. I need to post a before and after of my latest one, I was convinced it wasn't going to make it, but now it's amazing.

I should add. THE LIVE ROCK WAS COLLECTED FROM THE OCEAN AND DELIVERED THE SAME DAY! Only attempt this if you can make similar arrangements. The rock had ABSOLUTELY NO ODOUR, apart from the ocean, and there were at least 10 to 20 live shrimp per box, as well as a host of other things.
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