Aquarium with water plants

Aquarium maturation – how to set up an aquarium without problems?

Aquarium maturation is a process that occurs in any new tank, and handling this stage correctly can help you to avoid many serious problems. So what to do when you decide to set up your first aquarium

You set up an aquarium and then what?

A newly set up aquarium with fresh substrate, filled with tap water, and a brand new filter filled with clean filter media is not a suitable place for fish to live. To become a safe home for them it must be colonized by bacteria and other microorganisms. Aquarium maturation is the period of time when the tank is colonized by desirable bacteria, including what are considered the most essential ones – nitrifying bacteria.

Nitrification (nitrogen cycle in the aquarium)

Lack of developed bacterial flora in a new aquarium means that allowing fish into the tank at this stage, usually ends tragically for them. Why? Fish, like all organisms, excrete feces which get into the water. As a result of the decomposition carried out by bacteria, they become a source of nitrogenous compounds. Ammonium ions (NH4+) appear in the aquarium. The more alkaline the water, the more ammonium ions (NH4+) are converted into ammonia (NH3), which is highly toxic to fish.

In a mature aquarium, you will not find these compounds, as nitrifying bacteria from the Nitrosomonas group will quickly break them down to nitrite (NO2-). Which are also extremely toxic to fish by the way. But again, in a mature aquarium, another group of nitrifying bacteria will convert them to relatively safe nitrates (NO3-). Unfortunately, there are no nitrifying bacteria in the new aquarium. They have yet to populate the filter and substrate. This happens slowly because these bacteria are quite demanding. They need the right conditions and do not multiply very quickly. Therefore, experts assume that it takes about 4 weeks for the aquarium to mature.

When can you let the fish into a new aquarium?

This is one of the most frequently asked questions by beginning aquarists. Many people would like to buy an aquarium, pour the water in, hook up the equipment and let the fish in. Remember, never do that. This will lead to many problems and often fish death. 

A maturing aquarium should never have a full, planned population of fish. The more fish in the aquarium, the more ingredients that produce toxic nitrogen compounds.   

As I’ve mentioned before, nitrifying bacteria grow slowly in the aquarium. Therefore, if you let fish into the aquarium during very first few weeks, you will see high concentrations of ammonium/ammonia ions (NH4+/NH3) and nitrite (NO2), which as you already know, are toxic to fish. As a result, the new inhabitants of your tank will be in great danger. A maturing aquarium should never have a full, planned population of fish because fish are the main source of nitrogenous compounds. The more fish in the aquarium, the more ingredients that produce toxic nitrogen compounds. The aquarium is safe for fish when you detect only nitrate (NO3) with aquarium tests. This means that full nitrification is taking place in the aquarium.  

Here are some ways to help aquarium mature

Aquarium maturation with fish and product with bacteria

After pouring the water into the tank and starting the technical equipment, it is worth using water conditioners such as Tropical Antychlor + Tropical Esklarin with aloe vera or Tropical Supreme. They will remove chlorine and bind heavy metals. In addition, they will make fresh water more friendly to future aquarium inhabitants. After a few minutes, you can add Tropical Bacto Active – a mixture of different bacteria strains to the aquarium to facilitate the colonization of the aquarium by nitrifying bacteria. It is the saprophytic bacteria, decomposing organic matter, that will release, among other things, ammonium ions (NH4+), necessary for the nitrification process.  At this point you can also start adding Tropical Nitri-Active – a product with nitrifying bacteria – to your aquarium.

After another 1-2 days you can introduce the first fish (2 or 3) from the planned stock into the tank. Many aquarists choose guppies as the first fish “colonizing” the tank, due to their quite high resistance and flexibility to water parameters. If you have aquarium tests, track changes in nitrite (NO2) and ammonium ion (NH4+) concentrations as the aquarium matures. Also keep a close eye on the behavior of fish. Don’t forget to do small water changes (20 -25%). After each water change, treat the water, and add Tropical Nitri-Active (divide the weekly dose 20 ml/100 l for a new tank, if you change the water more than once a week). If the fish behave normally and the tests do not indicate ammonia and nitrite, you can let the next batch of fish in. Remember, take your time. Aquarium keeping is a hobby that requires patience. Don’t forget to learn all about quarantine of new fish.

Aquarium maturation with product with bacteria

In many older publications you will find that it takes about 4 weeks for the aquarium to mature, and that is how long you should wait to let the fish in. Nitrifying bacteria indeed take about that long to appear in a new tank. The problem is that to maintain biological balance in the tank you need really a lot of them. And as you already know they need energy to live, which they get from nitrogen compounds. But they are almost non-existent in a new aquarium. However, plants can also be a source of nitrogen compounds for them. Plants usually lose their leaves before they take root. Generally speaking, something will always die, break off, and eventually if you don’t specifically remove the debris, it will decompose.

So waiting 4 weeks to let the fish into a planted and bacteria-fed aquarium is not a bad idea either. However, if you let the full stock in after this time, monitor the nitrogen compounds in the water. Do frequent water changes and use products with bacteria. Because the system may not yet be ready for such a load of feces and urea.

Aquarium maturation with the help of a mature tank

Another method to achieve good results is to inoculate a new aquarium with bacteria from a mature one. However, there is one condition. The fish that live in a mature tank must be healthy. How to do it? Rinse the filter cartridges, collect this water and pour it into a new tank. You can also install a filter to mature in a working tank beforehand. Then you will move the filter to the new aquarium. However, I assume that if you are reading this text, you are at the stage of setting up your first tank and this method will not be useful at this point.

Aquarium maturation with active substrate

Tanks, in which the active substrate for plant cultivation was used, are particularly difficult. These types of substrates release micro- and macro-elements into the water when flooded. This results in massive algae growth and deterioration of water quality in the aquarium. Generally, an inexperienced aquarist may want to give up at this point. That’s why it’s important to plant as many plants as possible from the very beginning – after all, that’s what the active substrate is for. They don’t necessarily have to be target species right away. In addition, provide them with sufficiently intensive lighting and CO2 fertilization. At the same time, perform regular daily large water changes (30-50%). This type of substrates are willingly used in shrimp tanks, which are not usually heavily planted. Here, during aquarium maturation, you can flood the tank with RO filter water to flush out excess nutrients. But this is already a topic for another article.  

dr inż. (Ph.D.Eng) Aleksandra Kwaśniak-Płacheta

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