This was most excellent. I will be setting my tank up with my son every other weekend (divorce) this gives us plenty of time to cycle. I had no idea so much was involved. With my last tank (many, many, years ago) the only thing I was instructed to do was to make sure I had a UGF - a good filter - and a few fish to sacrifice. Fortunately the sacrifice fish never died, in fact they outlived several of my prized fish. Thanks again .. warped1

thank you, this in an excellent description of the necessary process. I've never seen one with the degree of detail I wanted.

I would recommend against the UG filter, and stick with a nice HOB (as long as it is adequate in size for the tank). The substrate from a previous tank will be perfect as long as you do not have any diseases you do not want to transfer to the new tank. Otherwise, make sure the tank has been dechlorinated prior to adding the substrate as it will have a large amount of beneficial bacteria that will cycle you tank quickly. Goodluck, and glad I could help!

UG filters operate by using the substrate (sand/gravel) to house the beneficial bacteria and convert the ammonia to nitrAte. The problem is that you create a nitrAte factory within the substrate and under the plate that builds up very high levels. With coarse gravel you can have waste material fall through the cracks which then rots underneath or in the substrate, and with fine gravel/sand you can have poor circulation. But the worst thing of all is in order to clean the filter you basically need to tear the entire tank down to get to the plates under the substrate. This is a messy ordeal that is not fun and what typically happens is people just never do this and you will have steadily increasing nitrAte levels regardless of water changes. With a HOB you just remove the inserts, wash them in some tank water and stick them back in. HTH

Great article, well i whas wondering about another technique involving vodka. Alcohol is supposed to be superfood for nitrifying bacteria. I personally have had good results with it. (Only 1 or 2 drops in the filter media). Could this be considered a trick to make it go faster?

thanks for the tip about light during the cycle, my ammonia levels have been staying really high and nitrite levels only just began to show after 3 weeks. i couldn't figure out why! planeria started appearing and algae, and now i know why.

Too early in the morning for me without coffee. Wanted to edit my above comment to say that planaria don't eat the algae, rather they eat the microorganisms that eat the algae. Bottom line still holds true; cut out the light and they will disappear.

Hi Yev, True algae requires light for photosynthesis. Without light, the algae dies. Since our bacteria do not require light to grow, that is why we recommend keeping it dark to prevent algae from growing in the first place. Now all new tanks will get diatoms which are not algae, but a brownish powdery (when rubbed off the surface) organism, which feeds off the silicates present in new tanks (glass and plastic surfaces). These may look like algae to the untrained eye, but is easily identified when removed from the surface. Best course of action? Wrap a black plastic garbage bag around the tank to prevent light from getting in. If you have a Hang-on-back (HOB) filter you can get away with lower the water level a bit to get enough oxygen in the water for the beneficial bacteria. If using a canister filter, it is probably a good idea to add an air pump to make sure there is enough desolved oxygen. Keep the room dark if possible, tank lights off and don't peek for a week. After that time the algae should be gone.

Yev, See my last post again. You CANNOT peak for at least a week. Algae is a very sneaky thing. Just like we can "survive" on water for weeks, algae can survive for quite a while even with brief amounts of light. You have to keep the tank sealed from light at all times for at least a week and your algae problems should be mostly fixed. Also, if you didn't start with a seed material (filter material or gravel from another tank), 5 days will not be enough time to show any change in the ammonia level. My recommendation would be to wrap it up completely (since you have an air pump), and ignore it for at least a week. Then you can test the ammonia level (but if possible try to do it in the dark! :)

Aaron, While Human Urine (in a healthy person) does contain the equivalent of a low dose fertilizer such as Seachem's Flourish, I would recommend against using it for cycling purposes. Depending on the person's hydration level you could also be adding in quite a bit of salt, not to mention difficulty in quantifying how much nitrogen you actually put in the water. To top it off urea (main nitrogen compound in human urine) is more difficult to metabolize for the bacteria than ammonia, and it is possible a different strain of bacteria is required which would not benefit the cycle. Either way, stick to the pure ammonia at the $0.99 store, just make sure it does not contain surfactants (soaps). If you look at the label it will often under ingredients say surfactants, but the surest way to test is after buying shake it up and pour some out. If it heavily foams you don't want to use it. Goodluck, and keep the urine in the toilet, or at least not on edible vegetables. I hear shrubs and flowers love it. ;)

Hi Kerry, Do you know if your tap water has chloramine instead of chlorine? If so you could use that (with a dechlorinator such as Prime). My understanding is that Prime will dechlorinate the water while detoxifying the ammonia (but leaving it able to be consumed by the bacteria). Otherwise dollar stores, and maybe ethnic grocery stores (if nothing around you has it). Trust me its out there, just not always easy to find. As for the cycling, the only product I know of that has been proven effective is a product known as BioSpira. This product contains live bacteria for the cycling of a tank and *can* be extremely effective. However it needs to be stored refrigerated, and DURING all times prior to you buying it. And that is typically the problem. Somewhere in shipping someone may not treat it properly and you'll spend a bunch of money for nothing, and risk killing your fish (since they recommend adding all of the fish and the BioSpira at once). Stick to used filter media. While diseases CAN transfer, most will not be viable due to the long period of time between cycling and fish addition. Remember most of these parasites and diseases require the fish/snail host to thrive. Take that away and they "starve". Goodluck and thank you for reading the article!

Darby, What size tank and how many and what kinds of fish do you have in there? First things first, stop feeding the fish. This will only contribute to the ammonia problem, and they can easily fast for several days without hurting them (they are coldblooded after all and have much slower metabolisms than us). I would feed a VERY small amount once every 3-4 days until you no longer detect ammonia/nitrIte. You need to get a liquid ammonia/nitrIte/nitrAte test kit and keep an eye on your levels. Before even that though you need to start doing large water changes as you are definitely getting ammonia and nitrIte buildup since you don't have a cycled tank. I would recommend 50% at least once a day until you get the test kit. After that you can check and do water changes when your levels get above 0.25ppm ammonia/nitrIte. I would also recommend going to the fish store and asking for a handful of gravel (if they have gravel in some of the tanks). Or see if you can get a couple plastic plants or decorations from the tanks (they will be coated in beneficial bacteria). If those options fail buy a couple low light plants (real plants, I don't know if what you have now is real/fake), but monitor them carefully. If the plants start to wilt or loose their leaves, get them out ASAP or they will contribute to the ammonia problems. I would keep your lights on for ~8 hours per day. You will likely get an algae problem but that will be beneficial to the fish since the algae will be consuming the ammonia. Please make sure you are using a good dechlorinator such as Seachem's Prime when you do water changes, and make sure the temp of the water matches the temp in the tank. Hope this helps, but please remember you need to be very active right now to keep the water conditions safe for the fish!

Darby, please reread my reply to your original post. In that I mention water changes are to be done with water that is the same temperature as the tank temp, and dechlorinated prior to adding the water to the tank (I use a 5 gallon bucket). The test strips are junk. Go and get a good liquid test kit such as the Aquarium Pharmaceuticals kit (~$15-20 and includes all the tests you need). Now the best part: That gravel is PERFECT for what you need. It will be coated in beneficial bacteria that will quickly cycle your 20G tank. What you need to do first though to avoid a possible ammonia spike due to uneaten worms is to wash the gravel in USED TANK WATER. Do NOT use tap water. The chlorine/chloramine in the tap water will kill the bacteria and make it all but useless. Instead, save your water in the 20G tank when you do your water change and use it to wash the gravel gently. Lighter debris such as uneaten food, poo, and other particles will get stirred up in the gravel and then you can just pour off all of the water. I'd recommend draining all of the water from the gravel before adding it to the 20G tank. As long as you don't let the gravel dry out the bacteria will be fine. If you like the look of the gravel just evenly spread it out on the bottom of the 20G tank. If you already have nice gravel or don't want the stuff from the catfish tank you can put the gravel in a mesh bag (they sell these at pet places for holding ceramic beads, carbon, etc.). I and many other people just use a cut up piece of NEW pantyhose (cannot have been washed with detergent!). You just need something to hold the gravel but it needs to allow constant water flow through to establish the bacteria. Goodluck!

Do me a favor and test your tap water for ammonia. If you detect any ammonia you will know your water has chloramines. Chloramines are more stable in water and so do not evaporate quickly (and therefore are great from a water safety standpoint), but for us aquarists it poses a problem because you can't just let water sit out to release the chlorine. When the chloramine molecule reacts with something, the amine is released (which becomes ammonia). So basically what I'm saying is if you are using a proper amount of dechlorinator when adding new water the amount of ammonia you detect in your tap water can be subtracted from your tank level since there is no way you'll have zero ammonia (well unless you have lots of plants and do very infrequent water changes). That amount of ammonia in the tap water has been neutralized and so doesn't count towards your toxic ammonia level. If you don't detect any ammonia in the tap water you need to do MULTIPLE back to back large water changes (25-50% is not large enough). It is quite possible your level rises faster than your water changes. Say you had an ammonia level of 1.0 and your BGK (even fasting) generates 0.5ppm a day. If you do a 50% water change you're only lowering the level from 1.0 to 0.5, but in that time the BGK raised it back up to 1.0. So if you continue to only do 50% changes a day the BGK will be in very bad shape (possibly irreversible gill damage). I highly recommend (again if you don't see any ammonia in your tap water) that you do 75-90% water changes until you get a value BELOW 0.25ppm ammonia. That is the max safe level I personally recommend during cycling. Once you get it down to a detectable level you can see just how much waste the BGK is producing and tailor your water changes to it. It is not uncommon for people to have to do multiple (2-3) large water changes A DAY until the bacteria multiply to a large level. Yeah it stinks, but it needs to be done. And remember the larger the water change the more important that you have VERY close temperatures between the tank water and the water you are adding. Added stress from temp swings is NOT good when already in a weakened state due to the ammonia. In the meantime PLEASE keep the feedings to very infrequently (once every 3-4 days), and then only a reasonable amount. While hungry, the alternative (ammonia or nitrIte poisoning) is much MUCH worse for the fish. Goodluck and keep up on the water changes!

Glad I could be of help. Actually one nice thing about having tap water with chloramines present is if you ever decide to use live plants. Every time you do a water change it's like giving them a small amount of fertilizer (nitrogen only of course). Free is good!

No need to take him out during the water change. As long as he has enough water to be fully submerged he'll be fine. What I'd recommend though for reducing the stress is to have some water ready to add (dechlor, same temp) when you drain down that low. That way as soon as you are done removing the water you can add the water back so he's only in that really low water level for a minute or two. And don't worry, he'll thank you for the reduction in ammonia!

Great article!!! I just restarted the tank after a 5 year break and completely forgot about the cycle. Thanks for all the great info. Very helpful!!