Fishless Cycle

As any of you who have met me on the boards knows, I'm a big proponent of fishless cycle. A while ago, Kimsfish asked me to write down some of my thoughts to be recorded for posterity (who knows why). Well, it took me a few weeks (ok, months...sorry Kim), but here it is.

Introduction

Before we can have a discussion of fishless cycle, we need to make sure everyone understands what we mean by the term "cycle." The Nitrogen Cycle is the most important thing we need to understand as fishkeepers. It's chemically a very complicated process, but here's the Cliff's Notes version. Fish produce ammonia (by urine and gill excretion), the problem is that ammonia is very toxic. Now, in nature, the currents in the water just carry the waste away until it's processed. In the home aquarium unfortunately, we don't have that luxury, what we do have however, is millions of little allies. Those allies are in the form of bacteria, probably of the genus Nitrosomonas, these bacteria take the bad ammonia and convert it to nitrite. Great huh? Not really. Nitrite is just as, if not more toxic than, ammonia, so the process repeats itself, just with a new set of bacteria, probably from the genus Nitrobacter, and the end product is nitrate which is far less toxic but in high levels can still cause problems, this form however is remedied through waterchanges and tank maintainance.  For a bit more in depth discussion of the Nitrogen cycle, check out the "Nitrogen cycle" section on main page.

Now, what do we mean by "cycling" a tank? Cycling a tank is simply building up colonies of bacteria that are large enough to handle all the ammonia your fish produce. Now, the nitrifying bacteria are all around us, in the air we breath and the water we drink, all we need to add is a food source (ammonia) to get them to multiply in our filter. There are two ways of going about this. The first is the "traditional" method of putting a few hardy fish in the tank and hoping they survive the stress of the cycle. The second method, the point of this writing, avoids the stress on the fish by artificially adding ammonia. This is what we mean by the fishless cycle.

How do I fishless cycle?

As I mentioned above, to cycle a tank you need to add ammonia. If you do choose to reduce the stress on your fish, and fishless cycle, the first thing you need is a source of ammonia. This one's pretty easy, just run down to your local grocery store and pick up some clear ammonia. Make sure it's clear ammonia with no perfumes, surfactants, or other additives; the label should say something like "clear" or "pure" ammonia.

Now that you have your ammonia, the fun begins. Add ammonia until your test kit reads 5ppm (you do have test kits right?). Since different brands off ammonia have different concentrations, there is no formula for "x amount of ammonia per gallon," you just need to keep testing. Once you've added you ammonia, test daily and try to keep the level above 5ppm. The exact amount isn't really important, just make sure the bacteria have a constant supply of food.

Every few days, test for nitrites. After a few days (or maybe a few weeks) you should see your nitrite level slowly rise, peak and then start to drop off. As the nitrite is dropping, you should start seeing nitrates. Once your nitrite registers "0" your tank is cycled!

Ways to speed up the cycle.

There are a couple of ways to speed up the cycle. The first is simply to raise the temperature of the tank. Chemical reactions are accelerated at higher temperatures, which causes the bacteria to divide faster. Be careful not to raise it too much however, over a certain point, bacterial growth is impeded. I've found the mid- to high-eighties work well. Obviously this won't work in a tank that is already stocked, you don't want to end up with cooked fish!

The second way to accelerate your cycle is to add "seed" bacteria to your tank. The more bacteria you have, the faster they'll be able to multiply. There are a few ways to add bacteria, the easiest (and cheapest) way is to take some gravel or filter media from an established disease-free tank and add it to your own. It's also possible to go down to your LFS and buy some sort of bacteria-in-a-bottle additive (Cycle, Stress-Zyme, etc.). The use of these products is very controversial amungst fishkeepers abroad as to whether or not the really do in fact work. the choice is your in this really, its your money.

Thank you for taking the time to read this and consider fishless cycling. If you have any questions, feel free to e-mail me, or better yet, post on the message board.