Cycling A New Tank

So you may have heard me talk about cycling a tank. But what exactly does that mean?

Fish create a fair amount of ammonia waste, and also any uneaten food will decay and produce ammonia. Ammonia is toxic to fish and will kill them if not removed. Thankfully there is bacteria in the world that just love ammonia and will happily use it, creating Nitrite in the process. That’s actually a bad thing as Nitrite is even more toxic to fish than Ammonia is … but once again there is a nice little bacteria that will use all it can find creating Nitrates (with an a) in the process. And yes, you guessed it, Nitrates are also toxic to fish, but far less so than Ammonia or Nitrite.

Unfortunately, there is no bacteria that will break down Nitrate into something non-toxic to the fish. To remove it, you have to do a partial water change each and every week, this water change not only removes Nitrates but other trace toxins as well. It’s easy enough to do and will only take a few minutes of your time, remove at least 25% but you can go as much as 50% and be fine.

If you test your water daily you can see the cycle progress. First you get a spike in ammonia, then it dies down and you see a corresponding spike in Nitrite. That then goes back down to zero and the Nitrates climb. Once ammonia and nitrites are both zero the aquarium is fully cycled and ready to go. This whole process takes at least 2 weeks, but more often 4 weeks … and can take up to 8 weeks. You read correctly, weeks, not days. So how do you start this cycle?

There are several different methods. The one most often used, usually out of ignorance, is to put fish in day one as your source of ammonia. This however is also the worst option available as it is very hard and stressful on the fish and so very often they don’t make it through alive. Some species are more hardy than others for surviving this process but the bottom line is … why use this method when there are alternatives that will do the same thing?

These alternatives are called fish-less cycles, and as the name implies you don’t use any fish. One method is to just feed the tank fish flake food as if you had fish in the tank. The food will break down into ammonia and start the cycling process. Once your ammonia and nitrites are gone, you use a gravel vacuum to suck up all the remaining excess food and put the fish in. This is a very imprecise method though as you never know exactly how much ammonia you are creating in the tank.

A more precise method is to put pure ammonia in the tank every day. The key word here is PURE ammonia, so no you can’t just use a bottle of windex as that has dye and fragrance and other garbage that is not good for fish. You put in enough to read a couple ppm (say 4), and you then put the same amount of ammonia in each day. Much like the other methods you’ll eventually see nitrites, and then nitrate. You should also read 0 ammonia the day after adding it. I highly recommend this method if you won’t want to deal with live plants.

Live plants? Yep, they’re the quick and easy method. A fully planted tank is instantly cycled because plants take up ammonia, nitrites, and nitrates all as food (they want the Nitrogen). In fact, they take it up so fast the regular bacteria can’t compete with them. You need a FULLY planted aquarium though, a few plants won’t cut it BUT even a couple plants does help. The faster growing plants remove the toxins faster than slower growing plants (of course). Does this mean you can skip the weekly partial water change? No, not at all. You still need to remove the other trace toxins, plus tap water contains trace minerals the plants use as nutrients.

Questions? Ask away.

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