Nitrogen Cycle Not Starting?

You’ve set up your tank, aquascaped it creatively with a good amount of live rock and turned the pumps, protein skimmer and filters on. You’ve even obtained a piece of fresh shrimp to add ammonia to kick-start the nitrogen cycle and it has been slowly decomposing in the aquarium for the past 3 or 4 days. In fact, it has even taken on a shade of reddish-pink, looking like a piece of boiled shrimp.

You’ve also broken out your newly acquired test kits and have been eagerly testing for ammonia and nitrite everyday, looking for the tell-tale sign that your nitrogen cycle has started to kick in. For good measure, you’ve attached a Seachem Ammonia Alert badge to the side of your tank so you’ll be the first to notice any spikes in ammonia when you walk past.

nitrogen cycle not starting

Fresh live rock instantly cycled this aquarium

But nothing.

No detectable ammonia is showing up on the test kit or the Ammonia Alert badge, and no nitrite either.

You go to the LFS to get a nitrate test kit — you had read that you would need one only after the third or fourth week — and you get another ammonia test kit for good measure, in case the first one was giving a false reading.

Wait a minute, this all sounds remarkably like… ME!

A seemingly non-existent nitrogen cycle was one of the first baffling things I encountered when I started my first saltwater aquarium in 2004. I thought something was wrong and that my tank, for whatever reason, was not cycling. And it is precisely for this reason that I am writing this article.

While there was a lot of information available on the web about the nitrogen cycle and how to cycle a saltwater aquarium, none of the sites mentioned anything about aquariums that defied conventional wisdom that every new tank must go through the typical cycling stages of ammonia to nitrite to nitrate!

And there was only the tiniest glimmer of information online of what might be happening in my tank.

The Nitrogen Cycle Is Going On — Whether You Can Measure It Or Not!

I’m fortunate to be living in a region that is the ornamental fish and livestock exporting hub of the world.

When my local fish shops get a shipment of liverock, usually from Indonesia, it is prime quality and extremely fresh. Usually no more than 48 hours has elapsed between the time of shipment from the source to our stores. The rock is also usually shipped wrapped in newspaper that is wet with seawater to help preserve life on and within the rock. And once in the hands of the dealers, the rock is put in holding tanks of fresh seawater.

In short, the live rock is alive as can be.

If your saltwater aquarium has not been going through the stages of the nitrogen cycle, consider this — it is very likely that your tanks biofilter of live rock has sufficient populations of denitrifying bacteria to consume and breakdown ammonia and nitrite from the very first day of your tank’s life.

And as is usually the case when there is a good amount of fresh live rock with no fish biolad other than the decomposing piece of shrimp meat, you probably won’t see much action from your protein skimmer either. Expect little to moderate amounts of light-colored, watery skimmate.

And to think I had notions of buying Florida live rock online (when Florida Live rock was still legally available), believing it to be better. The shipping costs would have run into the hundreds of dollars, and the rock would have taken more than a week to arrive. The long transit time would have meant that the live rock would have arrived in an uncured state, or semi-cured at best. That would have certainly put my ammonia test kits to good use!

When Will It Be Safe To Add Fish?

So you suspect your tank has instantly cycled, and you are getting constant readings over a daily basis of zero ammonia and zero nitrite. But that does not mean that you should be stocking your tank immediately with a whole bunch of fish and livestock!

On the unenlightened advice of one of local fish shops, I purchased two yellow-tail damsels (Chrysiptera parasema) to help kickstart the nitrogen cycle in my tank. One of the damsels died the following day, for reasons unknown. Determined not to lose any more fish, I gave my first tank a total of four weeks before I started adding any more livestock.

(As of this writing (12th February 2015), my other damsel, ‘Bluey’ is alive and well and going on to his eleventh year in my main tank!)

If your test kits have been measuring zero ammonia and nitrite in your tank for a good two weeks, you should now be seeing some nitrate in the 5 to 20 ppm range. This is an early indication that your tank has fully cycled. Do a 20% water change and slowly start adding one or two fish. Add one or two fish every week until you reach your quota for your tank size.

The idea is to not overburden your aquarium’s biofilter right away. The populations of denitrifying bacteria that are an integral part of the nitrogen cycle, will also increase proportionately to the fish bioload, but they need time to adjust.

Overburdening your tank’s biofilter will inevitably result in new tank syndrome and your will lose much of your livestock!

So if you are one of the few whose saltwater aquarium is not experiencing the normal, measurable ammonia and nitrite stages of the nitrogen cycle, count yourself lucky and take it to mean that your aquarium is off to a good start.

Read more about:

The Nitrogen Cycle

Water Parameters | Danger Levels

Nitrate In The Aquarium


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