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Nitrogen Cycle Explained

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NaH2O

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Many of you know all about the nitrogen cycle. Some new hobbyists, however, may know what it is, but not understand the process. Since I'm in the midst of cycling my tank, I thought it would be helpful to get the information out here for reference. I'll include my water parameters, and I'll try to get the different algaes that appear, as they occur.

The nitrogen cycle/process is bacterial driven. In a new system, we don't have the necessary bacteria present in order to break down organic material right away, so we grow it in order to establish a population. Since a new tank is void of these populations, there are a few things that can be done to jump start the process. The introduction of organic matter (i.e. die off in live rock, raw shrimp from the grocery store) to be broken down will get the system headed in the right direction. The decomposers use enzymes to break down proteins in dead organisms and their wastes, releasing nitrogen (other things like carbons are released, but I'll focus on the nitrogen). Proteinases break big protein molecules into smaller ones...peptidases break the peptide bonds and release amino acids....deaminases remove the amino groups from amino acids and release ammonia. As the ammonia builds in the aquarium, bacteria of the genus Nitrosomonas and related genera come in to convert the ammonia to nitrite (nitrogen is oxidized and energy captured by the bacteria). When testing, you will find ammonia rises....then the bacteria that break it down begin to populate ----> nitrites start to rise -----> ammonia starts to fall.

The next step of the process is nitrite converting to nitrate (again...nitrogen is oxidized and energy captured by the bacteria). The bacteria responsible for this is of the genus Nitrospira and related genera. In this situation, you will see a high level of nitrite.....then the bacteria that break it down begin to populate ----> nitrates start to rise -----> nitrites start to fall.

Nitrification is the term used to describe these two steps. It is the process of ammonia or ammonium ions becoming oxidized to nitrites or nitrates and is carried out by autotrophic bacteria. When it comes to our systems, the nitrogen cycle is an ever continuing process and always in action. Whenever there is organic material present - excess food, fish waste, decaying matter, etc. - it gets broken down and the process continues...over and over again. When adding livestock to the tank - it should be done in a reasonable time frame, so the bacterial populations have a chance to catch up to the new load. This way there won't be an accumulation of either ammonia or nitrites.

What happens with all that nitrate? Well, it can be utilized by algae, or if denitrifying bacteria are present, then it will continue through more processes with varying end products (denitrification). The denitrifying bacteria use nitrate instead of oxygen as a hydrogen acceptor under anaerobic conditions. Where are anaerobic conditions in the tank? More places than you would think. An obvious place would be in a deep sand bed, but anaerobic conditions are also present in live rock, and other surfaces of the tank. When bacteria are trying to consume something, they have to dissolve it in order to bring it into the cell. This area of bacterial snot will create anaerobic conditions within itself, as an example. Nitrate levels can also be reduced through water changes.

Next comes the fun algae cycles.....feeding off of dying bacteria and the nutrient rich environment.....new tanks will experience different algae growth before the tank is mature.
 

NaH2O

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My final plan of action for cycling my tank is no water changes until the very end of the cycle. This is so I don't disrupt or lose any of the bacterial populations I am growing. I won't have the lights on (except I may have them on 1 day to check for heat issues) until the cycle is over, and I am running my skimmer full time. I also added a 50 micron filter sock, once my rock began shedding detritus like crazy.

Here is my cycle as an example:

My tank was set up using 100% RO/DI water, 80F, 35ppt salinity (refract), and 170#s of uncured live rock. I purchased inexpensive ammonia and nitrite test kits, and a Salifert Nitrate kit. The pH is monitored via Pinpoint pH monitor.

Day 1 - 170#s of uncured live rock was temporarily placed in a tank with 60 gallons of water. 80F & 35ppt salinity. 2 Maxijets for circulation. Kept overnight in the "cess pool" until I could get help with aquascaping.

Day 2 - moved rock into the main tank & added new water + all the old water in the temporary tank.

Day 3 -
Temperature = 81F
pH = 8.13
Salinity = 35 ppt
Ammonia = 7.5
Nitrite = 0
Did not test nitrates

Day 4 -

Temperature = 80F
pH = 8.2
Salinity = 35 ppt
Ammonia = 7.5
Did not test nitrites or nitrates....I wanted to give them another day

Day 6 - nitrites on the rise

Temperature = 78.8F
pH = 8.14
Salinity = 35ppt
Ammonia = 7.5
Nitrites = 0.2
Did not test nitrates

Day 8 - nitrites and nitrates rising

Temperature = 79.2F
pH = 8.08
Salinity = 35 ppt
Ammonia = 7.5
Nitrite = 1 & above
Nitrate = 25

Day 9 - nitrates continue to rise

Temperature = 79.2F
pH = 8.07
Salinity = 35 ppt
Ammonia = 7.5
Nitrite = 1 & above
Nitrate = 50

Day 10 - nitrates still rising

Temperature = 79.5F
pH = 8.00
Salinity = 35ppt
Ammonia = 7.5
Nitrite = 1 & above
Nitrate = 100

Day 11 - Ammonia starting to drop

Temperature = 79.7F
pH = 7.83
Salinity = 35ppt
Ammonia = 5.0
Nitrites = 1 & above
Nitrates = 100

Day 12 - Ammonia still declining

Temperature = 77.7F
pH = 7.72
Salinity = 35ppt
Ammonia = 2.5
Nitrites = 1 & above
Nitrates = 100

Day 13 - Big drop in ammonia - almost gone

Temperature = 77.9F
pH = 7.90
Salinity = 35ppt
Ammonia = 0.25
Nitrite = 1 & above
Nitrates = 100

I'm starting to see some green cyano appear on portions of the rock. The rock is shedding detritus like mad - I'm blowing the rocks off daily with a power head.
 

BlennyBabe

Rachel
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Location
Gig Harbor Wa
My final plan of action for cycling my tank is no water changes until the very end of the cycle. This is so I don't disrupt or lose any of the bacterial populations I am growing.
You will loose bacteria. If it were to multiply at the same rate as when you added it to the tank, there would be no room for water within a month! The bacteria will die off in the cycle as well, its just a matter of it finding an equlibrium. The only thing that no water changes will do is to help reach that equlibrium faster.

I prefer to cycle slowly and do lots of water changes while lighting the rock. This way I can preserve as much life as possible. Both ways work. My method takes much longer and lots more work. It will increase diversity, both good and bad species.

I have done both methods and the end result is basically the same. Given enough time your rock will probably have just the same diversity as mine.

Good Job keeping track of the cycle progress. I think its essential to keep good notes. Have you ever heard of a product called aquarium journal? Heres a link. I want to try it. Ill probably get it when I get working again. http://www.aquariumjournals.com/index.php

Thanks for sharing.
 

CarlaW

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Columbia Falls, MT.
You ought to put a sticky on this thread. The info that will eventually be shown will be a great guide to anybody that is gonna lite a tank up. What about lighting, Nikki?:cool:
 

Curtswearing

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Nov 20, 2003
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St. Louis, MO
I saw some of those books at last years IMAC and they were very nice. Good idea.

Originally posted by NaH2O Next comes the fun algae cycles.....feeding off of dying bacteria and the nutrient rich environment.....new tanks will experience different algae growth before the tank is mature.
She pretty much says what you did regarding the bacteria.

I personally don't care if I kill off some bacteria when cycling a new tank as they will rapidly regrow as long as they have two things.....a place to live and food to eat. They will daily find an equilibrium and not just during a cycle. The loss of the normal amount of "nutrients" in the tank will cause the death of tons of bacteria. The addition of more "nutrients" than normal will cause an increase. Adding a piece of live rock, coral, or just about anything will cause a mini-cycle. It will create more habitat and will allow more bacteria to grow. This is why it is recommended to add livestock, etc. slowly......so each new addition doesn't overwhelm the current bacteria and you get a minicycle instead of a major cycle.
 
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NaH2O

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There are many ways to go about creating the cycle, and handling the nitrification process as it is occuring. I am just documenting mine for people to see how the nitrogen cycle functions.

Charlie - I hoped this thread would be very informative to many. I don't plan on having my lights on until the cycle is complete. Except for the one day that I'll turn them on to determine if I'll have a heat issue.
 

Elmo18

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Hi, this is a very informative post Nikki.

Regarding curing rock, and not cycling, I like to have lights on for couple hours during the day. This way I will not feed algal blooms to proportions, but i may be able to save photosynthetic flora/fauna that if, any survive the ammonia and nitrate spike.

I also do some water changes during this curing. I do like to keep as many things as possible 'alive', although i really wouldn't know if they are good or bad until a later time.

- Elmo
 

mojoreef

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Great thread Nikki. We will tag this one for the archives for sure.
On the losing of bacteria, that is a good plan, it will help reduce the algae blooms that are coming. When you first begin the cycle the ammount of food you put in to start it up will create a population equal to the ammount of food it has, it will be doughtful that you will ever have that much food available again, s populations of bacteria will die off for sure, and algae is usually johnny on the spot.


Mike
 

NaH2O

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Charlie, I am accumulating several days of tests, then I'll post them at once. I've reached a plateau, so actually my parameters haven't changed. I'm not surprised at all by this....if you could see the junk coming off the rocks, I'll be amazed if my ammonia ever reaches zero ;) . I'm going to try to get some of the rock out of the fuge and scrub more of the gunk off, and maybe siphon some of the detritus that has collected in the sump.
 

CarlaW

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Columbia Falls, MT.
Nikki,
If there is still that much coming off your rock, you will still probably have an ammonia reading for at least a week. Don't you think?
 

NaH2O

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Depends. If I get a large enough bacterial population, they should be able to process the die off as it is occuring. I siphoned detritus last night out of the sump & refugium. I also scrubbed the crap out of the rocks in these locations.
 

NaH2O

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Day 14 - no change

T = 77.9F
pH = 7.90
Salinity = 35 ppt
Ammonia = 0.25 ppm
Nitrite = 1 & above ppm
Nitrate = 100 ppm

Day 15 - no change

T = 77.9
pH = 7.87
Salinity = 35 ppt
Ammonia = 0.25
Nitrite = 1 & above
Nitrate = 100

Day 16 - no change, however, the ammonia test is taking longer to develop into the 0.25 ppm range on the comparison chart.

T = 77.9
pH = 7.88
Salinity = 35
Ammonia = 0.25
Nitrite = 1 & above
Nitrate = 100

Day 17 - no change - had the lights on today - checking for heat issues

T = 80.8F
pH = 7.85
Salinity = 35
Ammonia = 0.25
Nitrite = 1 & above
Nitrate = 100

Siphoned detritus out of the sump and the refugium. I scrubbed some decaying matter off of the rocks in both the sump and 'fuge. Added new water with the same salinity of 35 ppt, and I swapped out the 50 micron filter sock for a 5 micron filter sock.

Day 18 - no change, yet

T = 77.9
pH = 7.97
Salinity = 35
Ammonia = 0.25
Nitrite = 1 & above
Nitrate = 100

Blasted and scrubbed off some areas in the display tank. Also used a power head to get the bottoms of the overflow boxes.
 

NaH2O

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I Love Bacteria!

Day 22 - big drop in nitrite and a reduction in nitrate

T = 80.8F
pH = 7.93
salinity = 35 ppt
ammonia = 0.25 ppm
nitrite = 0.1 ppm
nitrate = 50 ppm

Day 26 - nitrate has reduced again

T = 80.8F
pH = 7.90
salinity = 35 ppt
ammonia = 0.25 ppm
nitrite = 0.1 ppm
nitrate = 25 ppm

Day 28 - siphoned more detritus out of the refugium....running the water through a 5 micron filter sock and back into the sump. Still a ton of detritus coming off of the rocks.

Day 29 - interesting how pH changes....I haven't done any water changes since the last one noted....just siphoned detritus

T = 80.1F
pH = 8.00
salinity = 35 ppt
ammonia = 0.25 ppm
nitrite = 0.1 ppm
nitrate = 25 ppm

Day 32 - blasted the rocks with a power head in the a.m.....siphoned detritus in the p.m. by running the water through a 5 micron filter sock and back into the sump.

Day 33 - began running the lights on a 12 hour schedule.

Day 36 - slight reduction in nitrites. GRRRR - still have a ton of die-off. I'm getting a lot of sponge material out of the rocks....no wonder there is still ammonia.

T = 80.4F
pH = 8.00
salinity = 35 ppt
ammonia = 0.25 ppm
nitrite = 0.05 ppm
nitrate = 25 ppm

I love growing bacteria.....where's my culture media and petri dish? :D
 

NaH2O

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Day 37 - Algae begins to grow

Day 38 - Water Params are the same, and I will probably take the water in to get tested at the end of the week, if they are not coming down any more. Just to get another opinion.

Here is one picture of the cyano I have growing:
 

NaH2O

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Here is another shot of the same rock from the side. There are also diatoms present:
 

MINIATUS

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Messages
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Thanks Nikki for the great thread. I have learned a lot from this and most other things you post. I knew I should have paid attention in Science class, but was to busy burning thinks with the gas lines and bunsen burners.

MINIATUS

:rolleyes:
 

NaH2O

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hmmm....good question - with this tank....probably not. The process is the process, and it takes the time it takes - I would want as much water volume as possible when curing rock, and my tank provides the most water I could have in one place. I could have done several tubs and rotated the skimmer, but it seemed like extra work, when I had the tank sitting right there. Also, I was much more comfortable taking time to aquascape with uncured rock out of the water than I would have been with cured rock (or even partially cured). I really wanted good flow on the rock and heavy skimming, so what better place than in this tank. I have been very happy with the closed loop and its functionality, I am still amazed at how well it works. One thing I keep reminding myself is all the rock is uncured - not a piece was cured rock from another tank.....I need to exhibit some patience. :)
 
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