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  • Cycling Your Tank

    Christopher Marks

    When a new aquarium system is created, the beneficial bacterial colonies that process excess waste are not immediately present. They will be introduced into your system when your live rock is added and will grow within the porous rock. The process that triggers the cycle into starting is kind of like a reverse process. There will be denitrifying bacteria present on the live rock that you add, but there will be no waste available to feed them. As the bacteria and other life begins to die off on the rock, ammonia will be created. This new ammonia feeds the remaining bacteria, which will then start the cycle process. Other simple methods may be used to start the process sooner, such as adding a very small amount of fish food, which will decay into ammonia.




    The exact amount of time that the cycle is going to take in a new system is difficult to predict. On average, it can take anywhere from two weeks to a month. If the rock is 'uncured', it may take longer for the existing die off to decay. If the rock is 'pre-cured' or 'cured', then the cycle process should complete quicker, as this rock contains very little excess dead life. More information on these liverock choices can be found in our Live Rock Selection article.
    So what should you do during the cycle? Keep your lights running on their regular 10-12 hour schedule. Do not cycle your tank with the lights completely off, unless you want the life on the live rock to die off, excess algae on uncured rock, for example. Do not perform any partial water changes during the the process, as doing so will stall the cycle from completing. Some people have experimented with doing very small water changes during the cycle to keep the ammonia levels from getting extremely high. The thought behind this method is that it will help preserve the life that came on your live rock. The benefits, if any, are not well known at this time however.

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    Thank you for making this so simple to understand!



    I agree! but is there a gallons-time ratio on how long the cycle would take? I have a JBJ 24G and I haven't started, I'm assuming that depending on the amount of live rock and live-sand I decide to put the wait-time would go down. Corrrect?

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    I do not believe there is as the cycle, is the cycle. Now, you can purchase Nutri-Seawater which is "taken from the ocean" and can add livestock same day. There is good and bad to this from what I've read. My JBJ 28G is mini-cycling as I moved tanks. I add Biozyme everyday as well as pH buffer because I had brain farts and used tap water...ok I was lazy and didn't go to the RO unit at our local super market..But I will be using RO or Nutri-Seawater for water changes and then just RO water after I've done a few changes to help with this bacterial growth.

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    I have heard to keep the lights off during a cycling process. I almost no LR in my DT. All of it is in the sump. Should I have a light down there?

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    I've kept freshwater for years... can I use my API freshwater kit to test my new nano reef's nitrogen cycle?

    I would think yes, but want to make sure! ?

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    Great article! I’m wondering, when should i do my first major waterchange? 
    My tank is 20 g and its been cycling for 2 weeks today.

    Been dosing with Aquaforest Bio s bacteria the past 14 days. And i put in the final dose today.

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