Setting Up Your Low-Tech Non-CO2 Planted Tank

Setting Up Your Low-Tech Non-CO2 Planted Tank

Many aquarists transition from keeping freshwater fish to keeping a planted aquarium, while some are interested in a planted aquarium from the start. Whatever the case, if you’re looking to set up a planted tank, you may be overwhelmed with the daunting amount of often-conflicting information out there.

When setting up a planted tank, one of the first decisions to make is whether you want a high-tech or a low-tech setup. A high-tech setup usually includes CO2 supplementation, high-output lighting and the like – see our guide here. Contrastingly, a low-tech setup usually does not include CO2, has lower-output lighting and a less-intense fertilization regimen.

Why do aquarists supplement CO2?

Unlike animals, plants produce their own food through a process known as photosynthesis. This requires water, CO2 and light, and releases oxygen. Micro- and macronutrients are also required, but are not shown in the diagram.

Most plants grown in home aquariums don’t grow fully submerged in nature. They’re actually bog plants and have some exposure to the air, which has a higher CO2 content than the water. This means that when grown fully submerged in planted aquariums, these plants don’t get as much CO2 as they would in nature, so aquarists supplement CO2 to augment plant growth.

What are the drawbacks of CO2?

Although CO2 achieves the “wow factor” in terms of plant growth, it comes with its own host of problems. To set up a CO2 system properly you’ll need to make a substantial overhead investment, significantly adding to the cost of your initial setup. Setting up and maintaining a CO2 system also requires a steep learning curve, and any errors (for example overdosing and asphyxiating your fish) can be detrimental.

What are the benefits of a low-tech, non-CO2 planted tank?

A low-tech planted tank is cheaper, and also requires a lot less hassle than a high-tech setup. The water chemistry isn’t nearly as complex, so doesn’t require constant testing and adjustment. Maintenance of plants is also must less demanding, with less time spent on pruning and a very minimal fertilization regimen. Finally, algae growth is much slower, so any imbalances in nutrients are not met with massive algae blooms, giving you much more time to correct these imbalances.

What are the drawbacks of a low-tech planted tank?

The main drawback of a low-tech planted tank is that plants simply don’t grow as quickly, which can be frustrating. If you’re planning to prune and rescape constantly, you may become bored with this approach. Some types of plants are also not compatible with a CO2-free setup, so you may have a more limited selection of plants.

Setting up your Low-Tech Planted Tank

If you’ve decided that a low-tech setup is for you, there are some special considerations in terms of lighting, water chemistry and plant selection that you’ll need to take into account. We’ll also discuss the selection of optimal substrates, fertilization and fish species to get your low-tech planted tank off to the best possible start.

Water chemistry considerations and fertilization

Let’s start by discussing some water chemistry considerations specific to low-tech setups. The lack of CO2 supplementation in a low-tech planted tank means that photosynthesis (and therefore plant growth) will occur at a much slower rate. Accordingly, plants will not take up micro- and macronutrients as quickly. Plants can sometimes even survive only on nutrients provided from fish waste and decaying foods.

Three macronutrients important for aquarium plant growth are Nitrogen (N) Phosphorous (P) and Potassium (K). Generally, you want to maintain about 10ppm nitrates, 1-2ppm phosphates, and 10ppm potassium. This is known as the NPK ratio.

If you’re relying on fish waste alone, you may not attain a proper NPK ratio, and nutrient imbalances can stunt plant growth. However, any fertilization regimen needs to be very modest and undertaken with caution, as nutrients will not be taken up nearly as quickly in a non-CO2 tank.

Once you have properly cycled your new tank , test NPK levels about a month after your tank is set up. Per the recommendation of Tom Barr’s EI dosing, dose weekly with the following per 20 gallons:

  • 1/4 Teaspoon Seacchem equilibrium
  • 1/8 Teaspoon Potassium Nitrate (KNO3)
  • 1/32 Teaspoon Potassium Monophosphate (KH2PO4)

It’s also recommended to skip this dosing about once every two months such that any imbalances in nutrients can be cleared up. Through this process, you can maintain non-limiting amounts of nutrients without risking an overdose.


The substrate is the basis for your planted tank, and it’s imperative to select the right type for your low-tech setup. Our substrate selection guide can help you assess the different kinds of substrates currently on the market, and properly install substrate in your new tank. A quick reminder – be sure to rinse substrate prior to placing it in your tank.

Notably, we do not recommend soil-type substrates for low-tech setups, as these substrates are infused with macronutrients that may not be absorbed quickly enough by plants that do not receive CO2 supplementation. To play it safe in this regard, we recommend porous substrates such as EcoComplete or Flourite.

EcoComplete contains denitrifying bacteria, and you can also purchase commercial preparations as Seachem Stability. Alternatively, you can use sediment or filter media from an established tank to help boost your biofilter.


Lighting is extremely important in a planted tank, as it is the driving force of photosynthesis. Absolutely do your research far and wide, but remember that many lighting guides are written under the assumption that you’re setting up a high-tech, CO2-supplemented planted tank. There are some special considerations for a low-tech non-CO2 setup that we’ll outline here.

If you are not supplementing CO2, this will likely be the rate-limiting component of photosynthesis for your aquarium plants. This means that increasing lighting in terms of wattage or photoperiod will not improve plant growth, but instead will encourage excess algae growth, and may be detrimental to your plants.

For a low-tech setup, you’ll want to target about 1.5 watts per gallon, and not exceed 2 watts per gallon when using fluorescent lighting. Because you’re actually looking for a lower-intensity light, fluorescent lighting is likely the way to go for a low-tech setup. If you do opt for higher-output lightings, such as T5, limit lighting to 1-1.2 watts per gallon. Remember that for taller tanks you’ll want to increase this slightly, and decrease for shallow tanks.

When you first set up your tank, shoot for a photoperiod (lights-on time) of around 6 hours, and increase to 8-9 hours after a couple of weeks. We don’t recommend increasing your photoperiod much beyond this. A timer is relatively inexpensive, and the best way to ensure that your plants are getting the proper duration of lighting daily.

Planting and Aquascaping

It is advisable to start with a relatively high density of plants, to begin with, as this will best balance out your water chemistry, and help your tank cycle. For a low-tech setup, we recommend starting off with inexpensive, fast-growing stem plants, which will help absorb nutrients as your tank cycles.

In general, hardy plants that are tolerant of lower lighting conditions are more likely to thrive in a non-CO2 setup. Other than stem plants, java ferns, anubius and water wisteria may be safe bets. Higher-maintenance plants such as swords, tiger lotuses and the like may be better-suited to a high-tech setup.

In general, you’ll want to place tall, fast-growing plant species towards the back of your tank, and slower-growing species towards the midground. Anubius grow best when anchored to hardscape rather than rooted in sediment, while java ferns can grow well in either condition.


Good filtration with a flow rate of at least 10-15 times the tank volume per hour is important in any aquarium. When placing the filtration output, make sure it is placed such that water flows back into the tank unrestricted such as to create good water circulation.

Canister filtration is highly recommended for planted aquariums, as it provides good circulation and does not become clogged. Activated charcoal and Biowheel filtration are not recommended for planted aquariums, as these may pull nutrients from the water.

If possible, it’s best to start out with filtration media from an established tank, such that a healthy colony of denitrifying bacteria is already present in the media. However, this may not be possible in some cases, in which case commercial preparations of bacteria will be helpful.


Although it’s tempting to add fish from the start, this rarely ends well. We recommend waiting at least two weeks before adding any fish to your aquarium and carefully monitoring water chemistry.

Once your water chemistry has stabilized, add just a few fish. Many aquarists recommend adding a hardy species such as tetra. Algae blooms are common in new tanks, in which case you can try hardy algae-eating fish such as otocinclus, or instead add a few hardy algae-eating inverts such as nerite snails or ghost shrimp.