Lets Talk about the Nitrogen Cycle

[Wy Renegade]

Lets start off with a basic look at the nitrogen cycle. In our aquariums, the nitrogen cycle (or cycling) begins with the presence of ammonia and bacteria within our tanks. That ammonia can be introduced in the form of ammonia itself (either directly by the hobbiest), indirectly through the introduction of live organisms (primarily fish) which produce waste that contains ammonia, or through the biological breakdown of a dead organism (such as a cocktail shrimp). The aerobic bacteria within the aquarium (either introduced by the hobbiest via "living" sand or rock, or the addition of "used" aquarium water, or having arrived on their own from spores in the air) begin the process of converting the ammonia (NH3) into nitrites (NO2-). Both ammonia and nitrites are toxic to fish at the high levels they are present at during the initial cycle; so introduction of living organisms should either wait until this portion of the cycle is complete or the hobbiests should very closely monitor the levels of both substances and continually do water changes to insure that these substances never reach toxic levels. While the toxicity of the toxins present may not be enough to cause instant death, research has shown that exposure at less then deadly levels is chronic and significantly shortens the life span of fish. The "cycle" is typically completed when the nitrites (NO2-) are further converted by aerobic bacteria into nitrates (NO3-), and a large scale water change is completed to remove the end products (nitrates) from the aquarium. While in truth the nitrogen cycle at this point is not complete, the portion of the "cycle" we are primarily interested in is considered complete. To truly complete the nitrogen cycle, we need to take this process farther by introducing biological methods to continue removing nitrates over the long term as living organisms continue to produce waste which must be processed through the nitrogen cycle. These methods of biological control can include macro algae which take up the nitrates and convert them into amino acids and anaerobic bacteria (contained deep within the pores of LR and within anaerobic areas of the sandbed (found in both deep and shallow sandbeds)) convert the nitrates (NO3-) into harmless nitrogen gas (N2). By harvesting the macro algae from your system you continue to remove the nitrates. Even then, the nitrogen cycle is not truly complete. Cyanobacteria (also known as blue-green algae) found within the saltwater aquarium is a nitrogen fixer, meaning that it has the ability to capture nitrogen gas (N2) released by the anaerobic bacteria and convert it into ammonia (NH3), Nitrite (NO2-), Nitrate (NO3-), and use that to promote their own growth.

 

[beaslbob]

In addition to aerobic bacteria, plant life like Fw plants or marine algaes prefer to get their nitrogen from ammonia over nitrates.

So what can happen is that in a tank started with plant life and (assuming absolutely no aerobic bacteria) the plant life consumes the ammonia directly preventing the ammonia and nitrIte spikes.

Then as the aerobic bacteria build up and start consuming the ammonia, the plant life eventually runs out of ammonia and is forced to consume nitrates instead.

So the nitrogen cycle with plant life can be no ammonia spikes, no nitrIte spikes with at most an initial nitrate spike. (well small ammonia/nitrIte spikes lasting a day at most).

Then as aerobic bacteria builds up (usually a few weeks later) the nitrates drop down.

When I start a tank I have plant life as part of the very first initial setup. Then let the tank alone for a week. After that I add a small fish load (like no more then 1 male fish for every 10g or so) and not add food for the next week. Then I more fully stock up the tank and start very very light feeding.

Over the years I have found those simple procedures insure the nitrigen cycle is safely established with no stress to the fish.


my .02

 

[Wy Renegade]

Certainly true in those cases of plants and/or macroalgaes that are nitrogen fixers. However those plants and macroalgaes must have the ability to convert that ammonia to nitrites and then to nitrates. To my knowledge, no algae (which the exception of blue-green algae which is actually a bacteria) or plant has the ability to use ammonia directly, it has to be converted first. It would be interesting to see exactly which macroalgaes are indeed nitrogen fixers as I am sure that many that are, particularly those we typically conserder to be invasive.

 

[Tabasco1]

Can you please share what level amonia is acceptable during a spike and when you should do a water change? For instance, should you always keep you amonia below 1ppm during a cycle and anything above that do a water change? So if you are getting a reading of .5 or .25 you should not water change?

 

[Tabasco1]

afternoon bump

 

[Wy Renegade]

Can you please share what level amonia is acceptable during a spike and when you should do a water change? For instance, should you always keep you amonia below 1ppm during a cycle and anything above that do a water change? So if you are getting a reading of .5 or .25 you should not water change?

Really depends on if you are hard cycling or soft cycling. If you are hard cycling the tank, there is no general recommended level, some say 1ppm of ammonia, others will say 5pp of ammonia. Remember that in the true hard cycle, our goal is to build bacteria levels as quickly as possible, and we are not concerned with trying to keep any of the existing life on the LR (although some will typically survive even a true hard cycle). If you are soft cycling and trying to preserve as much of the Living organisms that are present on the LR that you can (and I really don't know why anyone would choose to do anything other than this after paying premium prices for true LR), ammonia levels should never exceed .5ppm. So as soon as you get close, you need to do a water change with pre prepared saltwater. HTH

 

[Tabasco1]

Thanks so much! Just need to know what to shoot for. I am hovering between .5 & .25 and just needed a guideline. I definately want to soft cycle and keep as much life as possible, as that is what the whole purpose was.

Wish I would have bought a different test kit though, the .5 and .25 are VERY difficult to differentiate. Aw well.

 

[Wy Renegade]

Here's an excellent article on "soft-cycling your tank" by a friend of mine.

Originally Posted by spanko

SOFT CYCLE
Now let’s talk a little about uncured rock. Rock taken right from the ocean, whether from an established reef or from an area that has had dry rock dropped into it with the goal of establishing it as live rock. This uncured rock comes to the retailer fresh from the ocean and is then shipped to local fish stores or in some cases direct to the aquarist with all of the life and the subsequent death on it. Some fish stores may turn it into cured rock hoping to get the higher price that cured rock demands. Or they may sell it as uncured rock. Some aquarists may put it directly into their aquarium to “cycle with” or they may cure it outside of the tank so that they can use it later. Some may cure or use it to cycle their tanks as noted above in a hard cycle where no consideration is given to how high the ammonia and nitrites get. This hard cycle kills off some if not most of the life on the rock they paid a premium to get. Remember it is less costly than cured live rock, however it is more expensive than dry rock that can be used in our tanks and just seeded with a pc. or two of live rock.

Soft cycling is a method by which the attempt is to retain as much life as possible on the nice live rock you paid a premium for. It starts the same as a hard cycle, get a glass box, add some substrate if desired, add the live rock and the saltwater. Here is where things change though. During a soft cycle the aquarist is advised to run the filters, skimmers, lights. He\she is also to monitor ammonia on a daily if not twice per day basis and if the ammonia is shown to rise to a reading of .5 they are to immediately perform a water change. And every time thereafter when they see a reading of ammonia at .5 boom, another water change. Keep the skimmer cup emptied, Keep the filter floss, pads etc clean. Do everything they can to keep ammonia below that magic .5 reading. Because you see. Live rock contains ….. er…..well…..life. And in a soft cycle we are trying are hardest to keep that life……um……live! You would be amazed at the life that will flourish under these conditions. Sponges, feather dusters, snails, plant, corals, worms, pods etc. etc. etc. all of the things that we are trying to replicate in our small glass boxes. All for a little more work and a little more expense, to get closer to a small system that more resembles the ocean that it originated in.

Soft cycling is not for everyone. Some of us require a more antiseptic looking reef tank. But for those of us that wish to observe life as it exists, both the good and the bad, soft cycling may be something that you want to look into on your next, or even first setup.

Thank you for reading, I hope I have given some a little information to think about.

 

[tomle]

welcome!

 

[AADEGROOT]

I am new to the hobby and I am currently soft cycling my tank. I guess my question is based on appearance of my tank. My tank is soft cycling but my glass on the inside is getting dirty (so my question is two part), is it recommended that I clean the interior of the aquarium during cycling? Is this normal during cycling?

 

[Daniel@R2R]

It's definitely not a problem to clean the glass, but I wouldn't disturb anything else. If by "dirty" you mean algae growth, cleaning is just something that has to be part of your maintenance. So, some dirtiness is definitely normal.

Sent from my SPH-D710 using Tapatalk 2

 

[fragmatic]

There is never a reason you can not clean your glass with a scrubber or blade. In fact that is something you will want to keep up with so it does not get out of hand. As far as cleaning the rest of the interior, sucking out over abundance of algae & waste products during a water change is a generally acceptable way to accomplish most of that. It is not important during the cycle period. During that period you are mostly in the "wait for mother nature" state of things.

AFTER THE FIRST REAL COMPLETED CYCLE STAGE ....I personally prefer to add a 2" -ish clown as soon as the spikes have settled to keep the bacteria multiplying. Clowns are darn hearty fish for that, plus they frequently are on the wish list of most reef tankers. I consider an algae bloom of some sort a blessing at this time and see it as a flag to start adding life form diversification in the form of several species of the first clean up crew. Where some new reefers fail here is by not feeding enough for the clean up crew to not starve for several weeks or months. By then IMO you will have enough healthy bacteria that you will be well on your way to a "feed heavy" discipline. I am absolutely in the feed heavy camp! ... but I do so with my eyes wide open for signs of over or under feeding.