Cycling a shrimp tank
In the next month I will be setting up a new shrimp tank for my Neocaridina. I wanted to look for more information about cycling a shrimp tank and decided to put my notes into a blog which might be useful for other new shrimp keepers.
I will be using my previous filter and about 25% of my current tank water (but new substrate and soil).
As always, the information is conflicting with so many different views on how long to do it for and methods – so I’m trying to make the best of it as a newbie who only got a C in GCSE Chemistry.
So what is cycling?
It’s all about getting rid of toxins and keeping the water in a natural balance that won’t harm the shrimp. The key thing with shrimp is that they don’t like change and very small amounts of ammonia seems to kill them. It’s also a process which must continue – so it’s not something you do once and forget about (although if your tank habitat is well balanced it looks after itself eventually).
The Nitrogen Cycle is all about how nitrogen moves between plants, animals, bacteria, the air, soil and water. We are concerned with how this occurs within our aquarium habitat.
The 4 main states include Nitrogen (N2), Nitrates (N03), Nitrites (NO2) and Ammonium (NH4). It is bacteria which help it change states. The part we are interested in is ‘Nitrification’ where harmful ammonia is converted to less harmful Nitrate.
Ammonia –> Nitrite –> Nitrate
Every body of water has a nitrogen cycle – even micro habitats in containers left out in the rain. Oxygen is also an essential ingredient.
Utilising bacteria, an aquarium will go through a state of being able to convert toxic ammonia (from animal waste, uneaten food, decaying plants, tap water) into nitrate which is not toxic (and excess is removed with water changes).
The slightest hint of Ammonia and shrimp will die – even before your test strips say it is present.
* Ammonia can also come from the soil you use in a planted tank
What is happening when the waste is converted?
The waste breaks down into either ionised ammonium (NH4) or un-ionised ammonia (NH3) [also called ‘free’ ammonia].
NH4 isn’t toxic to shrimp and is present if the pH is acidic i.e. below 7. However, in alkali water (above pH7) un-ionised ammonia forms (NH3) which will kill aquarium fish and shrimp – and keep rising if nothing breaks it down.
NH4 can be removed by the filter media. NH3 in high concentrations needs to be changed to a less toxic form.
The first change occurs where bacteria oxidise ammonia (NH3) – a by-product being nitrite.
The second change is where other types of bacteria convert the nitrite to nitrate.
- A note on Bacteria
Why is it important to understand the latest findings in bacteria that work in this cycle – because you might be considering an over the counter start up culture that you pop into your tank and it needs to be the right sort and not a type of bacteria based on old research.
Bacteria (Nitrosomonas europaea) are some of the nitrifiers that will oxidise ammonia. Other bacteria can convert the nitrite to nitrate.
It was thought that Nitrobacter winogradskyi was largely responsible for converting nitrite to nitrate, however, some research has found that in freshwater it appears to be Nitrospira. You can read more about these findings in this link.
What happens to the Nitrate?
Nitrates must then be removed with water changes – as they can harm aquatic life if left to reach high levels. However, in a planted tank, with shrimp, the plants will take up nitrates and help with removal. Some people prefer to do very few water changes in a planted tank.
Nitrates also can cause algae blooms – another reason to do water changes (especially in a tank with no plants). The cycle continues so that ammonia is constantly being converted – as long as you have enough bacteria to keep up, ammonia should be zero.
Can the Nitrate change back into ammonia?
The other half of the ‘cycle’ is called de-nitrification. This is where nitrate is converted to nitric oxide (NO) and nitrous oxide (N2O). Some may also turn back in ammonium which is eaten by algae and plants. Eventually the oxygen part is used up and the nitrogen goes into the air as nitrogen gas. Incidentally, blue-green algae (cyanobacteria) can use this nitrogen gas as ‘food’.
Getting the cycle going in a tank – growing ever larger numbers of bacteria.
The key is maintaining a cycle of stability. Cycling to a point of balance for the animals and plants you want to eventually have can take weeks or months. There is much debate about whether to go fast or slow – and even around exactly how you do it!
You want to only add animals a little at a time so that the bacteria colony can cope with the ammonia coming from the poo of your first animal(s) – the cycle needs to keep up with the new amount of waste. A week or so later, more are added, and so so until you gradually build up both your bacteria and tank animals to the level you choose. Snails poo a lot – so add carefully! I have just one in my nano shrimp tank.
- Do I need to add Ammonia?
Most people use the natural ammonia in a tank:
- Decaying bacteria (introduced from the water, air, even your hands)
- Decaying algae
- Micro organisms from rainwater (if used)
- Decaying plants,
- 1-2 fish or a few shrimp – *some fish / snail poo a lot and overload – but shrimp might not produce enough.
- tap water (note your tap water de-chlorinator might also remove ammonia so can’t be used to start a cycle).
- Soil – your substrate/soil might have ammonia in it (see substrate choices)
However, if you have a tank of just water (with ammonia taken out / purified/boiled/RO ) and inert gravel with no plants or animals, you might need to kick start it and get an ammonia source (natural or chemical). This where some people choose to add ammonia liquid or some fish food in to decay. It’s controversial though and can go very wrong with chemical imbalances, and not relevant to a planted shrimp tank (see below). Too much ammonia and the nitrifying bacteria can die!
What might be relevant is remembering that ammonia is toxic when the pH is alkali (above 7) so if you use chemicals or naturally have a pH below neutral, the cycle won’t start. This might sound good – no toxic ammonia, until the pH goes slightly above neutral (and pH will shift somewhat if you are borderline below) and all hell breaks loose.
- Do I need bacteria?
In nature, nitrifying bacteria are everywhere and the cycle happens naturally. In a tank you have a small enclosed habitat so bacteria are usually added from a shop based formula (see previous paragraphs). Bacteria grow in the ceramic media in your filter, on surfaces in your tank and under the soil / substrate (depending on soil type and aeration). Biorb tanks use the rocks which have a big surface area for the bacteria to thrive in.
- Help the bacteria
Your bacteria will love oxygen, heat at 27-35 degrees and a dark place to thrive where there is no turbulent water movement.
Types of Cycling
There are many ways to cycle a tank.
- Shrimpless cycling – non planted tank
A new tank may not have enough bacteria to cope with the quick conversion needed in a tank full of creatures .
In a cycled tank bacteria keeps up with converting the ammonia.
You aim for no ammonia and some Nitrate to show all is well.
Until the bacteria multiply to trillions, some ammonia may not be converted and stay in the tank – and kill the shrimp. If you have no plants and inert gravel, these levels of ammonia may be high but not be detectable by a test strip i.e. still be enough to kill livestock.
I use test strips when things go wrong mostly – so see if the deaths were an ammonia spike or something else.
This is one reason why you might cycle a tank with no animals in it.
- Dry start cycling in a planted tank – where water is added just to beneath the top of the substrate in a planted tank which then has to be kept moist.
- Silent cycling in a planted tank – No ammonia spike to notice because the tank is full of stem plants which use ammonia as a food source from the start (see below).
Cycling in a planted tank
A planted tank it is different because plants make good use of ammonia to keep it under control.
If you use soil in a planted tank – that can be the ammonia injection needed to start it going. Otherwise, choices can be natural decaying plant matter. If your soil doesn’t leach ammonia then most people cover the soil with some substrate, plant heavily and pop in some shrimp straight away. The bacteria can come from using some gravel or filter media from a previous cycled tank (that has not been washed) or ‘start up colony’ from an over the counter product of the right bacteria. The shrimp bio-load should be minimal so the bacteria will probably keep up ok all being well. Keep well oxygenated and the soil/plants/bacteria combo should be fine.
Basically you let nature do its thing and test for when ammonia is zero and nitrate is being read for reassurance (note you may not see the ammonia spike or even a lot of nitrate).
I started my first planted tank with no animals, soil that didn’t leach, filter up and running and an over the counter starter bacteria. I waited about 8 weeks before I added shrimp. I had no deaths from ammonia, healthy plant growth and good stable parameters.
I used test kits for ammonia (never saw a spike) and nitrates and nitrites.
If you have no shrimp – increase the temperature to 27-35 degrees C for maximum bacteria growth but not over 40.
Using over the counter products to remove ammonia – and a little about tap water.
Products exists such as AmQuel which reacts with free ammonia changing it to a non-toxic form (if you have no carbon in the filter). The higher your tank pH the quicker it acts. This original formula also removes chlorine an chloramine from tap water. Some water dechlorinator products just break down chloramine into an ammonia bi-product which has to be removed by your bacteria. AmQuel does not leave ammonia in the water according to it’s website. AmQuel Plus is a new chemical formula that says it ‘Detoxifies all kinds of toxic nitrogen compounds’ amongst other things.
Seachem Prime is another product that removes chlorine, chloramine, ammonia (binding nitrite and nitrate) and heavy metals. I have used Prime before as my dechlorinator before I switched to rain water. It is also one of those products, like AmQuel that renders ammonia harmless. Prime works by a process called reduction that all de-chlorinators use (chlorine gas is converted to chloride ions – a process that also breaks the bonds between chlorine and nitrogen within the chloramine molecule – producing ammonia). A second process then occurs to bind the ammonia to render it harmless. AmGuard is an emergency ammonia removal agent by Seachem. You can read more about how they work in their factsheet.
Keeping the cycle going
Some things might cause an ammonia spike which should be avoided such as:
- Over feeding – feed only enough that the shrimp will eat over 1-2 hours.
- Lack of oxygen – nitrate can transform back into toxic nitrite and cultures may reduce.
- Do not clean out all the filter medium – leave 25-50% which have the bacteria on them.
- An ammonia spike might happen if the bacteria die e.g. medications or extreme heat or being washed out by tap water during a filter change.
- Limit snails so as to not overload the tank.
- Dead animals – if you have a massive disaster with many deaths this can cause a deadly spike and kill what it is left.
Here are some of the things people get their knickers in a knot over – so it comes down to personal information seeking and deciding on one method.
- Do use fish food v. never use fish food as it causes algae blooms.
- Add snails first – they poo a lot v. don’t add snails they poo too much.
- Never do a quick cycle v. quick cycles are ok.
- Speed up the cycle with product such as Sachem Stability or introduce beneficial bacteria v. go oh natural
- Putting fish or shrimp in with ammonia present is inhumane v. no harm will come to them.
- Test kits work well v. test kits for ammonia are useless.
- Messing around with the gravel and over cleaning in the first months disturbs bacteria v. go ahead and clean.
ShrimpFever.com describes a complex system lasting up to 3 months involving differing layers of substrate and bacteria cultures. It also talks about feeding the bacteria, adding additives and enzymes. Personally I find this over the top.
Some likely truths…
- Cleaning your filter media or sponge in tap water will kill the bacteria and cause ammonia to rise.
- Leaving 25-50% of old filter material allows the cycle to continue.
- Soils can leak ammonia
- Nitrate can kill if it builds up – so water changes are good (levels less than 15ppm / 15mg )
- If you use an inert substrate, shrimp alone won’t produce enough ammonia to start the cycle (at levels good enough to start a cycle they will die) – the bacteria will then die too (see fish food controversy above).
- Snail poo is good for ammonia.
- Air is good – get the surface water moving to help.
- A proficient cycle is achieved around 3-5 weeks.