How to stabilize a new planted tank

The tank above was grown in less than 6 weeks in a tank that was not pre-cycled. This guide explains how to smooth out the maturation process for people who are in a hurry to finish their planted tank projects and do not have time to let their tanks mature normally.

What makes new planted tanks so unstable?

New tanks that are not biologically mature provide a volatile environment for the inhabitants. New aquasoil often releases ammonia and other volatile organic compounds as the soil transitions from terrestrial to submerged conditions. Free ammonia and pathogenic bacteria that feed on detritus cause stress to both animals and plants - this is one of the reasons why plants may melt in a new tank. This change in state also causes major changes in the microbial environment, as microbes more suited to the submerged environment evolve and replace microbes that existed in the previously terrestrial environment as the aquasoil is newly submerged.

All of these environmental stresses cause more sensitive plants to melt - tissue culture plants and exotic species or weak plant samples are particularly vulnerable. Sensitive animals such as Caridina shrimps also fare poorly in immature tanks.

The processes of biological maturation in the tank all take place at the microbial level, invisible to the human eye, but we can tell if they have taken place by testing and observing what is happening in the tank. As the microbial community in the tank matures, the ammonia cycle is completed and the bacterial biofilm binds the fine particles in the water column, producing crystal clear water. Beneficial microbes consume algae and other pathogenic bacteria.

One way to set up the biological system without risking the plants is to do a dark start - run the tank with substrate and filter in place, but without plants or lights for a few weeks. However, many aquarists do not have the patience or time to do a dark start.

In this guide, we describe steps to speed up the process and mitigate the harsh starting conditions of a newly planted tank, so that plants can skip the melting and adaptation phase and get into the growth phase quickly.

Diatoms, dull plants attacked by algae and poor growth are all common symptoms in a newly planted tank. By following the steps below, we can minimise or even eliminate most of the drawbacks while speeding up the maturation process. To see how we got rid of the diatoms above without algicides (result below), see our link on Solving algae issues without algicides.

Main goals in the first few weeks of a new planted tank

• Accelerate microbial propagation, and thus maturation of the tank
• Accelerate ammonia cycling
• Remove excess ammonia and organic waste
• Reduce free floating particulate matter and algae spores
• Reduce pathogenic microbes that cause plant melt and livestock stress
• Ensure that plants have enough nutrients and CO2 to acclimatize fast

Creating an ideal environment for microbial growth

At the heart of accelerating a tank's maturation is the creation of a conducive environment for beneficial microbes - primarily those responsible for ammonia cycling, algae consumption and pathogenic bacteria. These microbes tend to prefer aerobic conditions. For ammonia cycling bacteria, the availability of organic carbon, phosphates and magnesium will speed up their multiplication rates; ensuring good gas exchange and oxygen levels in the tank is very important. Even in a tank with a lot of aquatic plants, plants only produce oxygen during the light window of the day, which can be less than 1/3 of the day depending on the tank setup. Microbial activity is 24/7 and it is ideal to have good oxygen levels throughout the day.

1. Seeding the tank with starter bacteria/microbes.

Use a mature filter or mix some substrate from a previous setup into the new setup to seed the tank with microbes. Using some mature filter media in a new filter setup will also help. Adding commercial strains of bacteria can also speed up the process, but is inferior to seeding the tank with media from a mature set-up.

2.  Having good oxygen levels through having a clean water surface.

Ensure that the water surface does not become clogged with an oily film. Using a surface skimmer will ensure that the water surface is always clear. Surface skimmer inlets are particularly good because they pick up organic waste that collects on the surface of the water and feed it directly into the filter with oxygenated water.

3. Having good oxygen levels through having a good flow pattern.

Gas exchange only takes place at the surface of the water - it is important to be able to circulate oxygen-rich surface water with water layers deeper in the tank. Make sure that the flow pattern in your tank exchanges the surface layer of water in the tank with water deeper in the tank.

4. Aim for filter turnover between 6x and 10x.

For most tanks it is ideal to have a filter at least 6 times the tank size. This means that if you have a 100 litre tank, you will want a filter that has a flow rate of at least 600 litres per hour.

5. Plant densely from the start.

Plants stabilise the system by absorbing ammonia, heavy metals and providing a favourable home for microbial life. Aim to cover at least 50% of the tank substrate area with easy-to-grow plant species - avoid fussy species at the start. It is important to add sufficient nutrients/CO2/light from the start to allow plants to adapt well to the new environment.

A good flow pattern brings oxygen rich surface water to deeper water layers in the tank. A stronger flow brings debris and organic waste particles to the filter to be digested.

The use of a surface skimmer inlet to the filter avoids the formation of a surface film and feeds oxygen-rich surface water directly into the filter. Waste proteins that accumulate on the surface of the water are drawn directly into the filter for digestion.

Having a clean water surface, and a slight ripple across the surface layer of the tank gives good oxygen levels without needing the usage of air stones.

Aged media may look messy, but it contains useful beneficial microbes. Mixing old and new filter media is a good way to boost your microbial community without spending money on expensive commercial additives. Squeezing the detritus from old sponge filters into your tank or filter will also work.

Removal of organic detritus, excess ammonia, pathogenic bacteria, algae spores

For aquasoils and soil based substrates, high levels of volatile organic matter can be released when the soil is first submerged. Ammonia rich aquasoils can release high levels of ammonia. ADA aquasoil for example can release 10+ppm of ammonia within the first few days of submergence. This will require large, regular water changes for the first few weeks unless a dark start has been used.

Excessive mulm on the substrate can also trigger algae. The idea of a soil substrate getting dirty is an extremely strange concept to newer hobbyists - isn't soil just a collection of dirt? The organic waste that accumulates on the surface of Aquasoil is very different from the components that make up Aquasoil. This is better understood through the idea of composting - many gardeners compost their kitchen waste before adding it to their gardens. This creates a biologically stable medium compared to the overly labile conditions that would be created by adding raw kitchen waste directly to the garden soil. Similarly, Aquasoil is made up of weathered organic matter and clay, which is much more biologically stable than the undigested organic waste that accumulates on the substrate surface over time.

While the accumulation of organic waste on the Aquasoil substrate provides some nutrients, it does so at the expense of being a significant trigger for algae when high light levels are used. It is much cleaner to remove the unstable organic waste layer and fertilise the tank with pure elemental salts - this will result in fewer algae triggers.

This is done by hovering a siphon over the surface of the substrate while using a turkey baster to pick up surface debris. For weekly cleaning, do not aim to disturb more than the top layer of the substrate. For more details on how we do it, Click here.

1. Large water changes during the initial weeks.

For tanks using Aquasoil, we recommend water changes (70-80%) every 2 days for the first few weeks, then every 4 to 5 days for the following weeks. Once the tank has stabilised, a weekly water change schedule should be sufficient.

2. Siphon away detritus on the substrate surface during water changes.

Algae spores and organic detritus gather on the substrate surface. Siphoning away surface debris by water changing the 2hr Way removes detritus and minimizes algae blooms in a new tank. A clean tank environment reduces melting of newly introduced sensitive plant species.

3. Cutting away badly deteriorating old growth on acclimatizing plants.

As newly introduced plants acclimatise to the aquarium environment, they will produce new leaves optimised for the new environment. At the same time, they may shed older leaves and channel the energy into new growth instead. As the plants stop defending the old growth, the old growth attracts algae. Allowing the plant to refresh itself by cutting off old growth and making room for new leaves will significantly reduce algae in the tank.

4. Removing minor algae blooms manually during water changes.

Diatoms, green dust algae and BGA are common in new tank setups. Rather than using harsh algicides at this early stage of the tank, small clumps of algae should be skimmed off during water changes to prevent them smothering plant growth. We have more details on this in this guide on controlling algae without algicides.

Deteriorating old leaves are an algae magnet. These can be removed as the plant replaces them with fresh new leaves that are resistant to algae.

Trimming off old growth reduces over-crowding and gives space for new algae free growth. 

Ensure plant growth parameters are in place

Deteriorating plants contribute to organic waste levels and are a prime target for algae. Good growth parameters are essential for plants to adapt quickly to new tank conditions and a large, healthy growing plant mass is the fastest way to stabilise a new tank.

1. Aim for high CO2 levels (if injecting CO2)

High CO2 levels greatly accelerate the growth and adaptation of aquatic plants. Newly introduced plants, which may have been grown emersed, must adapt to extract CO2 from the water column when submerged. The biological machinery for extracting CO2 is energy intensive and the availability of sufficient CO2 will greatly speed up acclimatisation.

2. Dose a comprehensive water column fertilizer.

Many aquarists avoid fertilising their newly planted tanks because newly submerged aquasoil is rich in nutrients. However, newly introduced plants will not have developed root systems and will have limited ability to extract nutrients from the substrate. These plants will use their internal energy stores as well as drawing nutrients through the water column, so having all the essential nutrients in the water column will allow the plants to acclimatise more quickly.

Fresh aquasoil often releases ammonia, which can provide nitrogen for plants. However, nitrogen is not the only nutrient that plants need to grow. Many of the other nutrients required, such as magnesium or potassium, are not released significantly into the water column by aquasoil - they may be present in the soil matrix, but the plant must have an established root system to access them. The addition of a complete fertiliser to the water column is therefore very helpful for newly introduced plants.

Signs of tank maturity and stabilization

As newly introduced plants acclimatise to being planted in a tank, they tend to channel their energy into producing new leaves that are adapted to the new environment. New leaves that are well formed and healthy produce defensive chemicals at the molecular level that deter algae from attaching to them and also prevent damage from microbial decomposers. Observing new leaves that are large, well-formed, well-coloured and free of algae is a sign that the plant is adapting well. Old leaves are shed and the plant stops defending itself against both microbes and algae.

Deterioration of older leaves is an expected symptom of newly introduced plants. These leaves can be cut off to make room for new growth. In the case of stem plants, the healthy upper part can be replanted and the damaged lower parts uprooted and discarded. There are many signs that tank stability is moving in a positive direction:

1. Signs of healthy new growth.

Plants will produce new growth adapted to the new tank conditions. If the plant has successfully acclimatised, the new leaves should be very resistant to algae, even if the older leaves are attacked by algae. You can then cut off the older leaves to make room for new, algae-free growth. In time, the entire tank will be very resistant to algae with fresh new growth.

2. Cloudy water turning crystal clear.

Matured biological systems have plenty of bacteria bio-films that bind fine particulate matter down and keep the water crystal clear. Beneficial microbes keep pathogenic bacteria down, creating a healthier environment for livestock.

3. Ammonia cycling complete.

Ammonia readings would diminish to zero as the tank completes its cycle. In lower pH tanks, this could take a couple of months.

4. Reduction of algae.

As the tank matures, the incidence of algae should decrease - diatoms and green dust algae, which are more common in freshly planted setups, should disappear on their own as plant growth accelerates. Plant growth will remove algae over time and microbial herbivores will also reduce algae in the tank.

What if the tank fails to stabilize?

Tanks generally start to stabilise quickly as plants acclimatise to the new tank environment and start to grow fresh new growth free of algae. However, there are many variables that can set the process back, such as lack of equipment, poor tap water quality, weak initial plant samples, poor substrate choice and more. On the other pages of this site we describe how to optimise each element, but due to the limitations of each hobbyist for regional or budgetary reasons, changing tank equipment or other essential parts of the system may not be feasible. In the hobby we often have to make the best of what we have. These are the few steps you can take if the system cannot stabilise itself with the steps above.

1. Patience. How long to wait?

Tanks can sometimes take much longer to set up. A misstep that crashes the system or a spike in plant stress can delay plant growth for weeks. Plants will also take longer to adapt if tap water quality is questionable or other growth parameters are not met due to equipment limitations. Give the tank time - low tech (non-CO2 injected) tanks can take a few months to stabilise and start growing well. A low tech tank should not take more than 6 months to stabilise. For a CO2-injected tank, taking more than 3 months could be a sign that there are more serious fundamental problems with the setup being used (or that it is a poorly optimised setup).

2. Changing out plant selection.

The choice of plant species has a huge impact on the outcome of the tank. Plant species vary greatly in their requirements. Replacing difficult/difficult plants with easier ones is one way to make progress in a difficult tank. Sometimes moving a difficult plant to a more optimal position in the tank can also help with borderline cases.

3. Tune down the light. At least for the short run.

Algae is the biggest problem for most tank setups that fail to stabilise. Turning the light down can greatly reduce algae problems. Once the tank has stabilised, the light can be turned back up. This is an important factor that is often ignored by most people as it is difficult to measure light levels in the tank without more specialised equipment.

All aquatic carpets can be grown with 40-50umol PAR on the substrate as long as CO2 is adequate. Most green plants will grow well at this level, although higher light levels may produce more compact growth. Red plants will start to develop good colour at around 100 umols PAR. Even the most demanding species can start to grow between 100-150 umols PAR. Whilst some species will develop better colouration and density at higher light levels, we can start tanks at lower light levels to allow stability to set in. This is especially true for tanks that do not have demanding plants that require a lot of light.

Lower light levels make algae management much easier. However, PAR meters are expensive and most hobbyists will have to guess the PAR levels for their tanks. This Iwagumi uses only 40+ umol PAR on the substrate. This low light level also makes it easy to keep the hardscape free of algae.

Conclusions

By following the steps above, tanks can be brought to a good level of maturity in about 6 to 8 weeks. The pictures above and below show the difference after 45 days from first planting. The more delicate species such as Hygrophila chai and Eriocaulon species were added after the first 2 weeks.

There are many other factors that can confound the hobbyist's journey that are difficult to control, such as the quality of the tap water or the quality of the freshly introduced plants. However, good maintenance and tank cleanliness will maximise the chances of success even if other factors are not optimal.

To learn how to prevent algae through smart tank design, click here.

To learn more about tank cycling and related articles, click here.

To learn more about gaseous exchange, click here.