A Guide to Growing Healthy Aquarium Plants

A Guide to Growing Healthy Aquarium Plants - Windy City Aquariums

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There is a lot of confusion out there when it comes to Aquarium Plants and all the jargon that goes with them. What in the world does "low tech", "medium tech", and "high tech" even mean?! Most people would define "low tech" as a tank without injected CO2 and "high tech" as a tank that has CO2 injected into it.

However, I would argue that the definition of "low tech" and "high tech" revolving just around CO2 is meaningless without considering the other elements that play just as much of a role as CO2 does when it comes to growing plants. There are three elements in what I call the "Trinity of a Planted Aquarium", AKA Light, CO2, and Nutrients as shown below:
Trinity of a Planted Aquarium
Yes, the parameters of your water (such as pH, kH, gH, and temperature) are important as well, but water parameters are not a significant factor that determines if your plants will thrive compared to the 3 elements above. As long as your water parameters are within an acceptable range, which should be the case for most tap water used, growing plants shouldn't be an issue.

Algae, which is a common problem that many people in this hobby face, usually occurs when there is an imbalance of one or more of the 3 elements in the "Trinity of a Planted Aquarium". To put it simply, the prescence of Algae means there is an imbalance in either light, CO2, or nutrients, which gives Algae the opportunity to outcompete with your aquatic plants and take over.

I know that the definition of low-tech, medium-tech, and high-tech will vary based on who you ask, but my personal definition is simple:
  • Low-Tech: NEITHER good* lighting nor CO2
  • Medium-Tech: EITHER good* lighting or CO2 (usually it is good lighting but no CO2)
  • High-Tech: BOTH good* lighting AND CO2

*"good" in my definition means medium-high intensity lighting, which I go more in-depth about here.

Notice that I don't include nutrients as a factor as you should always ensure that your plants have enough nutrients no matter if your tank is "low-tech" or "high tech"!
So now that you understand what the important factors of keeping your aquatic plants healthy are, I will go into more depth on the individual elements of the "Trinity of a Planted Aquarium".

1. Lighting

This is arguably one of the most important factors out of the three. Even with CO2 injection and sufficient nutrients, your plants will not thrive unless you have good lighting to help encourage your plants to utilize CO2 and nutrients to grow. Aquatic plants, just like normal land plants, go through a process called photosynthesis, where they use sunlight (or light in general) to synthesize foods from carbon dioxide and water to produce oxygen.

Color Temperature

Color Temperature

The color temperature of your lights is important as plants absorb light in the red and blue ends of the spectrum, so a color temperature between 6500k to 7500k will tend to have spikes in those particular wavelengths, which means more Photosynthetic Active Radiation, or PAR for short. Although 6500k to 7500k is recommended, most people would say 5000-10,000k is a relatively acceptable range. It's preferable that you make sure the light you get is full-spectrum or has a mixture of white, red, and blue LED lights. Some lower-end aquarium lights, such as the Nicrew ClassicLED Aquarium Light, which only has white and blue LED lights, which is TOTALLY fine as you have less demanding low-light plants such as Cryptocoryne, Anubias , or Java Fern. Again, most standard built-in aquarium lights will be fine for low-light plants, but for medium-high light plants, you will definitely need to consider upgrading to a stronger light.

Light Intensity

Another factor to consider is the intensity of your light, which is generally measured in PAR (Photosynthetic Active Radiation), as mentioned earlier. The problem with this is the intensity of the light you have can vary based on how deep your aquarium is. The intensity of your light dissipates as the depth or height of your aquarium increases. The same light that would be considered low in a taller aquarium, might be considered a high light in a shorter aquarium due to the shorter distance the light needs to travel to get to the bottom.

Light intensity needed also depends on what kind of plants you are trying to grow. While low-light plants don't need intense lighting, more demanding medium-high light plants, especially plants that are naturally redder in color, will require light with a higher intensity to be able to thrive. Since there's no real way to determine a light's intensity in your aquarium since it relies on a bunch of factors, so I suggest experimenting with different lighting to see what works best for you.

Light Spread

The final factor is how far your light spreads or diffuses/disperses. You'll want to get a light that is long or wide enough that all parts of to bottom of your aquarium are well lit. If not, the plants outside the area where the light covers might not get enough light. Again, this is something you will need to experiment with as the area a light covers may depend on how deep your aquarium is, the distance between the light and your aquarium, and the intensity of the light. In wider aquariums, you might need to get two or more lights parallel to each other to cover the entire width of the aquarium.

Lights That I Recommend Personally:

Now that I've talked about the different factors when it comes to lighting, here are some examples of aquarium lights that I personally use and recommend trying out based on the light intensity needed.
**CAUTION: These lights are VERY strong and honestly are considered over-kill for growing plants most of the time. With these lights you will 100% need CO2 and to fertilize the tank regularly to be able to keep up with the plant growth and to prevent algae from taking over, hence I suggest that only advanced/veteran hobbyists try using these lights. For the "MEDIUM-HIGH LIGHT" you most likely will need to at least dose fertilizers to keep up with plant growth and prevent algae.
Although not entirely accurate, you can use the Watts Per Gallon Rule to roughly gauge what a certain light will be considered based on the size of your tank:
  • Low Light: 1-2 Watts per gallon
  • Medium Light: 2-3 Watts per gallon
  • High Light: 3+ Watts per gallon
Flood Lights on an Aquarium
(Using Flood Lights on my 40 gallon breeder tank)
Other lighting alternatives that aren't specifically for aquariums that are commonly used by people in the hobby include: flood lights, and plant grow lights such as the Mars Hydro Plant Grow Lights. Just remember though, you don't need to spend hundreds of dollars on lighting in order to have a beautifully planted tank! I always recommend experimenting to see which light and plants work best for you.

2. CO2

As I explained earlier, CO2 is necessary for plants to be able to photosynthesize. Even without injecting CO2, small amounts of it can be found in your aquarium water as CO2 in the atmosphere around your aquarium will dissolve into the water, and it is given out by the fish and bacteria living in your aquarium as they respire/breathe. Without the injection of additional CO2, your plants' growth is limited to the amount of CO2 in the water.
Do note that injecting additional CO2 is definitely not as important as getting good lighting is, as many aquatic plants do not require the injection of additional CO2, and will grow fine without it as many they have adapted to the lower amounts of CO2 that is available in the water column. There's no point in adding additional CO2 if you do not have the lighting requirements to match it as plants need both light and CO2 to be able to photosynthesize.
Pearling Aquarium Plant
(Pearling - Aquatic Plants producing oxygen as a result of photosynthesis)

Budget-Friendly DIY CO2 Set Ups

Using a DIY CO2 Kit such as the Aquario Neo DIY CO2 Kit, or rigging up a homemade DIY CO system using yeast and sugar is a beginner-friendly, and budget-friendly way of injecting CO2 into an aquarium. However, I do not personally recommend these over a proper Pressurized CO2 set up, as they probably cost you more in the long run, and you can't control the CO2 production (especially if you are using a homemade DIY CO2 setup using yeast and sugar). Without having control over the amount of CO2 you're adding to your aquarium, you may end up accidentally "suffocating" your fish.
In addition, having an excessive amount of CO2 being injected into the water may lead  to rapid PH drops or PH swings, as CO2 naturally lowers the PH of water, making it more acidic. These Rapid PH drops or PH swings may end up "shocking" your fish and may eventually kill them.
The only time I would not be super concerned doing this is if you have a pretty big aquarium, or you're just starting out and haven't stocked your tank with livestock.

The Myth of "Liquid" CO2

Many hobbyists may claim they are injecting CO2 into their tank using "Liquid" CO2 such as API's CO2 booster or Seachem's Flourish Excel. However, this claim is false as CO2 in "liquid" form does not exist in normal atmospheric pressure and temperature, and only exists if it is highly pressurized, such as in a tank or canister from a gas supply company. "Liquid" CO2 products' main ingredients include Glutaraldehyde, which is an algaecide or biocide. Glutaraldehyde helps kill algae in your aquarium, which in turn allows your plants to have better access to the nutrients and CO2 that are already available within your aquarium. While these products are fine for combating algae issues, if they overused they may kill your your plants too.

Pressurized CO2 Set Ups

Pressurized CO2 Setup
(An example of a proper pressurized CO2 setup)
In my opinion, injecting CO2 is not that important if you have a Low Tech/ Low Light tank set up as most aquarium plants will do just fine without it, and I would usually suggest that you invest in a better light instead.
However, if you plan on setting up a High-Tech Tank, I would highly recommend getting a proper pressurized CO2 setup (and doing a lot of research before you decide to get it), and to not cheap out on any of the equipment, especially the CO2 regulator as this will control how much CO2 is released from the canister and will prevent any leakage of CO2 or "end of tank dump", which can happen with lower quality CO2 regulators. Generally, a proper pressurized CO2 system can start from around $100 or more depending on the equipment you buy.
If you would like to learn more, I would personally recommend watching George Farmer's video on setting up a pressurized CO2 system as he gives a pretty comprehensive overview on how to do so!

3. Nutrients

Nutrients in the water column come from either from poop/decaying matter, dosing liquid fertilizer or root tabs, or be present in certain active plant substrates such as CaribSea's Eco-Complete (I go into more depth about different aquarium substrates in my Guide To Choosing An Aquarium Substrate). Generally, adding additional nutrients by fertilizing is usually not really necessary for many slow-growing or low light plants such as Java Fern or Anubias Plants. However, if you notice that your plants are not healthy and show any signs of the nutrient deficiencies in the chart below, I recommend dosing either liquid fertilizer or root tabs depending on the plant and how it takes in nutrients (either through the water column or substrate, or both).
Plant Nutrient Deficiency Chart
(An illustration of common Freshwater Plant nutrient deficiencies)


You will notice that there are two types of nutrients plants need:
  1. Macronutrients: Carbon (C), Nitrogen (N), Phosphorus (P), Potassium (K), Magnesium (Mg), Sulfur (S) and Calcium (Ca). (Hydrogen and Oxygen are also macronutrients, but are readily available as they are taken in through water, H2O)
  2. Micronutrients: Iron (Fe), Manganese (Mn), Chlorine (Cl), Copper (Cu), Boron (B), Molybdenum (Mo), Cobalt (Co), Nickel (Ni).


    Macronutrients are nutrients that are needed in higher amounts and are considered essential in helping plants produce energy grow.
    1. Carbon (C) - plants get this from CO2, which can be found dissolved in the water or added by injecting CO2 directly into the water.
    2. Nitrogen (N) and Phosphorus (P) - poop from living creatures in your aquarium such as your fish or shrimp provides Phosphorus, in the form of Phosphates, and Nitrogen compounds such as Nitrate which are used by plants to build amino-acids, which are then converted into proteins which are the "building blocks" of plants. A well-stocked tank should be able to provide sufficient amounts of both.
    3. Potassium (K) - helps regulate the plants' intake of CO2 and begins the entire process of sugar production. Most water companies remove Potassium so it is generally not found in tap water.
    4. Magnesium (Mg) - a key molecule in chlorophyll, and can be found in most tap water but may need to be supplemented if you have softer water.
    5. Sulfur (S) and Calcium (Ca) - can be found in most tap water in sufficient amounts. Calcium is especially abundant in harder tap water.


    Micronutrients such as Iron (Fe), Manganese (Mn), Chlorine (Cl), Copper (Cu), Boron (B), Molybdenum (Mo), Cobalt (Co), Nickel (Ni) are required in smaller amounts by plants in order to keep their leaves healthy. This is important as most of the plants' chlorophyll, which is essential in photosynthesis, can found on the surface of their leaves. Iron (Fe) in particular, is debated by many aquarists to be the nutrient that helps give naturally red plants their vibrant red color. Although these nutrients are needed in smaller amounts, they are equally as important as the macronutrients, and without it, most plants will not thrive.

    Liquid Fertilizers or Root Tabs?

    Liquid and Root Tab Fertilizer
    For plants that intake nutrients from the water column (such as Anacharis, Hornwort, floating plants, and most stem plants), I recommend using our liquid fertilizer. For plants that rooted in the substrate where they mainly intake nutrients from their roots (such as Cryptocoryne Plants, Sword Plants, and carpeting plants like Dwarf Baby Tears), I recommend using our Osmocote Plus Root Tab fertilizer.
    Your frequency of dosing fertilizers depends on the type of substrate you are using and the rate of growth of your aquatic plants. Faster growing plants or plants that receive more light or additional CO2 will need more nutrients than those that don't, and if the substrate you are using is an inert one, such as Sand or Gravel, you will most likely have to fertilize your plants more often. To learn more, you can read our Guide To Choosing An Aquarium Substrate blog post.
    I suggest observing your plants to ensure they are not showing any signs of nutrient deficiencies, and to monitor your nitrate levels, ensuring that they sit around 5-10ppm at least. If not, I would recommend dosing fertilizer in your aquariums at least once or twice a week depending on how heavily planted your tank is.

    4. Conclusion

    Planted Tank
    Planted aquariums can be as easy or as difficult as you want them to be. If you're looking for an easy "low tech" planted aquarium, I suggest either reading my Top 11 Easiest Plants For Beginners blog post or browse our Low Light Aquarium Plants collection as many of the plants on the list thrive in almost any aquarium setup. If you feel that you are up for a challenge and are looking to get more invested into this hobby, I recommend trying some of our more advanced plants in a "medium tech" or "high tech" aquarium.

    A healthy planted aquarium (especially an algae-free one!) needs a balance of Light, CO2, and Nutrients, AKA the "Trinity of a Planted Aquarium", no matter if you're going for a "low tech" or "high tech" aquarium. I hope you have found this guide useful and I want you to remember that the amount of money you spend on your equipment does not always equate to healthier, more colorful looking aquariums! It's all about finding what works for you, and finding the right balance of Light, CO2, and Nutrients.


    1 thought on “A Guide to Growing Healthy Aquarium Plants


    Thy very much for this detailed guide <3

    September 25, 2022 at 03:19am

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