What Do Aquatic Plants Need to Survive?
Disclosure: I may earn a commission when you purchase through my affiliate links. As an Amazon Associate I earn from qualifying purchases. – read more
Plants are a crucial addition to any aquatic setup, especially one housing fish, crustaceans, and other life forms. That’s because plants come with a variety of benefits.
They will oxygenate the environment, control water chemistry to prevent excessive formation of ammonia, nitrites, and nitrates, reduce waste, and provide cover.
Your fish will be more sociable, energetic, and even more colorful and larger when kept in planted versus barebone aquariums.
Naturally, though, plants also require specific environmental conditions to survive and thrive, and this is what we’ll be talking about today.
Adding aquarium plants to your tank can be a bit confusing if you’ve never had aquarium plants.
The Basic Needs of Aquatic Plants
So, you’re ready to plantscape your aquarium but have no idea what your plants actually need to survive. Don’t worry, it’s not complicated.
So, let’s go really basic:
This is pretty much a given. Aquatic plants need water to survive, and this may sound like a stupid point that doesn’t even need mentioning.
Not quite, though. Many people overlook this simple and basic fact about aquarium plants, leading them to keep their plants dry until the aquarium setup is complete.
This can deprive the plants of necessary nutrients, which can cause death fairly fast. So, if your aquarium setup isn’t ready yet, make sure you keep your plant in water in the meantime.
This is a more complex topic, despite its, again, seeming simplicity. Sure, plants require lighting, but how much light is too much or not enough?
This is a legitimate question for 5 reasons:
- Different plants have different light requirements – Some plant species require low-light conditions. It’s not that they can thrive in low-light conditions, but they actually require them. Some noticeable mentions include java moss, java fern, hornwort, anubias barteri, green hygro, etc. Others demand higher lighting conditions, such as Vallisneria. Not providing adequate lighting can affect your plants, so this is a sensitive topic.
- Too much light – Yes, there is such a thing as too much light, both in terms of intensity and duration. Excess light levels will promote algae overgrowth, which will exacerbate the problem in the other direction. In other words, the algae will grow excessively, cover your plants, and block their access to adequate light. So, your plants will no longer be able to perform proper photosynthesis. The outcome is death in all cases in the long run.
- Tank depth – Your tank’s depth and overall setup also make a huge difference in the light intensity required. The deeper the tank is, the higher the light intensity required. This is to allow the light to penetrate the mass of water properly so that it can reach the deeper layers inhabited by other plants and lifeforms.
- Light type – Does your tank has access to natural sunlight? In that case, you probably won’t even need any extra artificial lighting source. If not, you need to consider one. Incandescent bulbs are out of the question due to their ineffective heat-light ratio. Incandescent bulbs only convert up to 10% of their energy into actual light, the rest being heat. Metal halides and fluorescent bulbs are more effective in this sense, converting approximately 45% to 60% respectively of the energy into light. So, you’re only left with LEDs, which generate less heat, have a longer lifespan, and are by far the most effective in terms of energy conversion.
- Color spectrum – Yes, the color spectrum also plays a critical role in your plants’ development. Sure, plants are resilient and adaptable, so they can work with pretty much any light source, including plain white LEDs. However, you want your plant to thrive, not only survive. In that case, you need to consider a specific light spectrum to provide your plant with additional benefits. The ideal light spectrum for most aquatic plants consists of a mix of red and blue, which supports better pigmentation and an improved growth rate.
As you can see, there are a lot of variables worth considering when it comes to lighting. Generally speaking, aquarium lights demand a light intensity varying between 0.25 and 0.8 watts per liter.
Your aquatic plants should also receive 8-10 hours of light daily for a stable day/night cycle for proper physiological functioning. That’s no matter the plant’s overall light requirements.
We should begin by saying that all aquarium plants require adequate nutrition, no matter the species, the plant’s size, type, or any other factors. When it comes to aquarium plant nutrition, consider the following:
- The type of plant – Rooted plants feed differently than floating ones. The former get their nutrients out of the substrate while the latter get them straight from the water column. This difference is critical because it informs you on the ideal approach when it comes to fertilization. You feed rooted plants differently than the floating ones.
- The type of substrate – Soil is naturally the best option for plants in general and aquatic plants in particular. You can get enriched, nutrient-rich aquarium soils specifically designed for aquarium use. These will provide your plants with long-term nutrient content, supporting their growth rate and nutritional demands in the process. However, inert substrates like sand and gravel won’t give plants any nutrients. At this point, you need to fertilize plants artificially to fulfill their nutritional needs.
- The type of fertilizer – Root tabs are common plant fertilizers for plant species planted in inert substrates. Sand is commonly used in the aquarium business, thanks to its esthetic value. The problem is that sand is devoid of any nutritional value, making it almost impossible for plants to survive in it. This is where root tabs come in, releasing nutrients into the substrate and feeding plants continuously over time. Different plants will require more root tabs than others. You also need to replenish your root tabs over time, as the old ones lose their nutritional value. Some plants need as many as 3-4 root tabs per week.
Other factors will also influence your plants’ nutrient intake, such as the presence of algae, adequate lighting, CO2 injections, plant overpopulation, etc.
Wild plants get their CO2 from a variety of sources, primarily from the substrate and the surrounding decaying matter. Nature is an open system (compared to an aquarium), allowing for the free flow of nutrients and chemicals.
By comparison, an aquarium only contains moderate levels of CO2 with a low capacity of producing more in high-enough quantities.
Your aquarium will produce CO2 naturally via fish waste, food residues, dead plant matter, etc., but it generally won’t be enough for your plants. At this point, you will need CO2 injections to regulate the levels of CO2 present in the tank.
CO2 is a major component in plant nutrition since plants use it to perform photosynthesis and produce oxygen during the day.
Your plants will exhibit signs of CO2 deficiency if there isn’t enough CO2 in your tank. Always check your CO2 levels and consider supplementing it if necessary.
Do Aquatic Plants Need Soil?
Aquatic plants can live in any substrate (pretty much) when provided adequate preparation and care. That being said, soil is the best option for aquatic plants due to its high nutritional value.
Soil emulates the plant’s natural conditions and offers a higher nutrient content than other types of substrates.
Sand and gravel are considered inert substrates due to them being devoid of nutrients, but there are other problems worth considering as well.
- Compaction – This is a sand-specific problem that most aquarists will struggle with. Sand consists of smaller particles that will compact when wet. In other words, the sand will ‘squeeze’ the plant’s roots, inhibiting its ability to extract nutrients and essentially suffocating them. This will hinder the plant’s growth and will even kill it if you fail to address the issue.
- Improper anchoring – Finer types of sand exhibit microparticles that showcase poor anchoring abilities. In essence, your plant’s roots won’t anchor themselves sufficiently well into the substrate and will become unearthed soon after being planted. The same thing happens when housing substrate-digging fish species that love to dig into sand. These will inadvertently unearth your plants since sand is so easy to dig through.
- Poor nutrient retention – This is more of a gravel-specific issue due to the larger particles and rocks it comprises of. Using root tabs will help your plants to some degree. The problem is that, because gravel consists of larger particles, the nutrients will seep into the water, escaping the plant’s grasp. Gravel also offers poor anchoring for the same reasons. To compensate for these issues, many aquarists use a layer of gravel on top of a layer of soil. The soil will provide the plants with nutrients and anchoring, while the gravel will come with the esthetic punch.
- Anaerobic pockets – This is another problem specific to sandy substrates. Because sand comprises of such small particles, there is a risk of anaerobic pockets forming under the substrate. These form due to the water not being able to circulate through the particles and consist of pockets of air when ammonia will form. These ammonia pockets are the result of bacterial activity, with the sand keeping the resulting ammonia trapped. Rooted plants will often pop these pockets, and the contact with ammonia trapped there will kill them. Substrate diggers may also burst the bubbles, releasing ammonia into the tank and potentially killing everyone.
I recommend nutrient-rich soils for adequate nutrition. Or you can go for sand; just be aware of the risks and difficulties coming with preparing the substrate for your plants.
Do Aquatic Plants Need Oxygen?
Yes, all plants require oxygen to ‘breathe,’ including aquatic species. Aquatic plants will consume CO2 during the day and produce oxygen during the photosynthesis process.
This process reverses during nighttime, causing the plant to consume oxygen and release CO2 into the environment. All plants undergo this simple process, including trees.
This can naturally lead to issues in overplanted fish setups. In short, the more plants you have, the higher the risk of your fish experiencing oxygen deprivation during nighttime.
That’s because everybody consumes oxygen during that time. So, you may need to consider an air pump if you have a lot of fish and plants sharing the same space.
Can Aquatic Plants Survive Without Sunlight?
Yes, aquatic plants can survive without sunlight. However, that doesn’t mean that they can survive without light at all.
Your plants still require a light source to be able to perform photosynthesis. We’ve discussed the specifics earlier in this article.
Aquatic plants are not difficult to keep and care for, provided you’ve got your basics down.
Learn about your plants’ essential requirements, craft the best setup for them, and they will provide you with multiple benefits in return.