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Cycling your tank WITHOUT fish

The Fishless Cycle

If you’re here, you’ve chosen well, young Padawan.

Fishless cycling has become more popular over the years, as fish keepers have become more aware of the dangers involved with fish-in cycling (to their fish), the inhumanity of it all, in addition to the speed at which cycling an aquarium can be obtained with the fishless method. Whereas the fish-in cycling can take months to colonize with the proper levels of beneficial bacteria (BB), fishless cycling can take approximately 2-3 weeks (sometimes longer, depending on the size of the aquarium).

There are several ways to fishless cycle a tank. You can use pure ammonia (my preferred method), drop some flakes of fish food in the tank (ghost feed), or drop one raw shrimp in the tank (usually in a media bag or even an unwashed stocking to keep it from getting too messy). For purposes of keeping things simple, I’ll be discussing the pure ammonia method below. If you’d like to attempt the other methods for some reason, please search for Cycling With Flakes and here for Cycling With Shrimp.

Ok, so let’s get on with it!

I’ll list the method with some easy to follow numerical steps to make this as simplistic a process as I can possibly make it. Let’s get started:

*Please note that throughout this entire process you should not change any of the water. Doing so will hinder your BB colonization and WILL delay your cycle. Please be patient throughout the process. I know how eager you probably are to add fish, change things around, etc. Also, you CAN add plants to your aquarium while cycling, BUT some plants can delay your cycle, because they’ll consume Ammonia, as well, and will compete with your Nitrosomonas marina bacteria.

Step 1: Purchase your aquarium, filter, heater, thermometer, substrate, any decorations you’d want (including plants), dechlorinator (ie – Safe or Prime), API’s Freshwater (or Saltwater – depends on your needs) Master Test Kit and pure, plain, additive-free Ammonia.
– The purest ammonia you can find can probably be found at the Dollar Store or a smaller hardware store, like Ace (not Home Depot or Lowes – they both have ammonia with additives). You can buy about a liter or so at the Dollar Store, you guessed it… for $1.
– A milliliter syringe.
– You will need the Test Kit to make certain your adding the correct amount of ammonia, in addition to testing your water’s parameters (checking for ammonia, nitrites and nitrates).

Step 2: Rinse your filter out with cold running tap water and fill it with sponge media (which is the mechanical filtration) and bio-media (which is your biological filtration – this is where your BB colony will grow). Your sponge can, however, hold a good amount of BB, as well. This media is all you’ll need. You won’t need anything else, including carbon (which is chemical filtration), ammonia-eating filtration that can be purchased (this defeats the purpose and won’t last forever), or anything else that isn’t a sponge or bio-media.

Step 3: Add dechlorinator, your substrate, equipment and decor. We recommend scaping your tank “dry” because it eliminates overfilling. Every item you add to the tank is going to displace water, best we not make messes this early!

Step 4: Raise the temperature of your heater to 82’F-85’F. You can keep it at your regular temp for your fish, but raising the temperature will create an optimal environment for growing your BB colony. They enjoy warmer temps.

Step 5: At this point use your milliliter syringe to add ammonia to the tank. We have measured that 25% of your gallon size is the amount of milliliters to parts per million. Example: 40g tank, 10 milliliters of pure ammonia.

Step 6: After about 15 to 30 minutes, allowing your filter to move the ammonia around, use your Test Kit to check the Ammonia levels. If it reads 2ppm, you’re ready to go. If it’s less, continue to add more until you’ve reached 2ppm Ammonia. If its slightly more, don’t panic, you’re still ok.

Step 7: Pick two times of the day you are available to make changes to the tank. We recommend a morning and a night time. In the morning test for ammonia. If it has dropped from the 2ppm level we first added, use simple math to add back what has processed out. We will get to the second test in a later step.

(example: 40g tank = 10ml of ammonia, Ammonia went from 2ppm to 1.5ppm, add 2.5ml of ammonia)

Step 8: After 24hrs to 48hrs, test your Ammonia parameters to see if they’ve dropped. If they have, you’re on your way to colonizing Nitrosomonas marina (the Ammonia eating bacteria). We want our levels to continue to stay at 2ppm in the morning. The amount of time this takes differs from tank to tank.

Step 9: Now that your Ammonia is dropping, you can begin testing for Nitrites. This may take one, two and sometimes three ore more days (again, this depends on the tank). Your Nitrosomonas marina bacteria requires time to grow – enough time to eat all of the ammonia you’ve added to the tank.

Step 9: Continue to test in the morning, once per day (preferably at the same time of day), until your Ammonia reading is consistently dropping lower and lower. At this time start testing at night as well. We want to monitor the fall of ammonia from 2ppm in a 12ish hour period of time. Only add ammonia in the morning testing time. Our end goal is that you add up to 2ppm of ammonia in the morning and come home to 0ppm ammonia at night. Depending on the size of your tank the growth of the colony can take longer. If Ammonia hasn’t dropped yet below 2ppm, or Nitrites aren’t present yet, don’t get discouraged. Every tank is a little different and not one tank will cycle as fast or slow as another. Be patient.

Step 10: Continue to test your parameters daily. Once you’ve reached a reading of 0ppm Ammonia in a 12 hour period you are close to done! At this point, start testing for a reading of Nitrites. Sometimes you will not see a single spike of Nitrites as they are quickly consumed and converted to Nitrates. If Nitrites are present, you have a nice colony of Nitrosomonas marina building, and you’re about to start building a colony of Nitrospira (the Nitrite eating bacteria).

Step 11: Continue dosing 2ppm Ammonia per day (when Ammonia drops to 0ppm – usually 24hrs will do it) and continue testing for Ammonia, Nitrites and begin testing for Nitrates. The forming of Nitrospira typically is the shortest portion of the cycle, so it may be hard to see Nitrites begin dropping and to start seeing Nitrates.

Step 12: Once you have a reading of 0ppm Ammonia, 0ppm Nitrites and 20+ppm Nitrates (more likely 60+ppm) you’re cycled!

Step 13: Do a 100% water change to eliminate your Nitrates as much as possible. You want a Nitrate reading of <= 20ppm (preferably <= 10ppm). Since the BB is in your filter, you can conduct as many water changes after your cycle, that you need to, until you’ve reached 0ppm Ammonia, 0ppm Nitrites and 10ppm Nitrates. Just be sure to use dechlorinator before adding the new water (for every water change). Chlorine CAN and WILL kill your newly grown BB… and after all of this work, you wouldn’t want to do that, would you?!

Finally: That’s it! You’re done and you’re ready to add fish, invertebrates and whatever else your big heart desires.

If you know what you’re doing and this isn’t the first time you’ve cycled a tank, you can fully stock the tank at this point, depending on if you can surmise how much biological bacteria you’ve grown in the tank. Your bio-load should provide your BB with enough food to live on a daily basis. If you grew enough for a full bio-load in a 75gal tank, then do your BB a favor and stock accordingly.

If you’re new to the game or you like to take your time in adding fish, only add as many as you’re comfortable adding. Keep in mind, however, that if you do add only a few fish in the beginning, you’re killing a good portion of the BB that you grew and you’ll only be able to add about three fish at a time, within a week or two of each other (ie – Week 1 = add 3 fish, week 3 = add 3 more fish, etc).

If, for some reason, you don’t have the stock you want yet, but don’t want your BB to die, just continue to dose 2ppm of Ammonia every 24hrs. Also, the need for a water change is not needed just yet. Do so directly before adding the first stocking of fish in the tank. This will keep your BB alive, but it will also end in raising your Nitrates. So, once you’re ready to add fish, you’ll need to do another large water change to take care of those Trates.

If you have questions, feel free to ask!

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