How to Fertilize Your Planted Tank the EASY Way

We're big proponents of getting live aquatic plants because of their natural beauty and ability to purify water, but a common question we get is, “Do I need to fertilize my aquarium plants?” From our experience, most people have to fertilize because fish waste does not provide the proper amounts of nitrate, potassium, phosphate, and other trace minerals that plants require to flourish. Another big factor is your local tap water. If you live on well water, your water may contain lots of heavy metals and high nitrate levels, which is not great for drinking but might be really good at growing plants. In contrast, the tap water at our fish store near Seattle, Washington is so soft and stripped of nutrients that it is almost like RODI (reverse osmosis de-ionized) water — which is perfect for raising discus fish but insufficient for plants.

Because everyone’s tap water, lighting selection, plant stocking, and tank setups are so different, some aquarium companies try to compensate by releasing many different types of fertilizers to address every corner case. Unfortunately, such a vast offering can be very confusing for someone just getting started with planted aquariums, so we sought to create an all-in-one Easy Green fertilizer that would help as many people as possible. Our Easy Fertilizer line only consists of four, beginner-friendly products that are geared towards planted tank setups with low to medium lighting and no CO₂ (carbon dioxide) injection. With this goal in mind, the vast majority of our customers have great success with Aquarium Co-Op fertilizers because they contain all the right nutrient concentrations for most aquatic plants. A small percentage of users already have so many nutrients in their water that they don’t need as much help from fertilizers. Also, some hobbyists may want to set up high light planted tanks with pressurized CO₂ that have specialized nutrient requirements to meet their objectives. To show you how easy the Aquarium Co-Op fertilizers are to use, let’s get started with a quick guide and figure out which of our fertilizers are right for you.

1. Easy Green

If you only get one fertilizer, Easy Green is the one you want. This all-in-one liquid fertilizer provides the correct ratios of macronutrients and micronutrients that plants need so that you don’t have to figure it out yourself. Like all of our fertilizers, Easy Green is completely safe to use with fish, shrimp, snails, and other invertebrates. While other fertilizers require you to measure out certain milliliters or capfuls, we offer two sizes of Easy Green with an easy-to-use pump head or dropper cap for quick dosing. (See the product page for the dosage instructions we recommend starting with.)

Since everyone’s setup and plant stocking density are different, we suggest you test the water each week at first to really dial in the fertilizer dosage. Rather than test for every single nutrient, the easiest way is to use a 60-second test strip and figure out how many pumps or drops of Easy Green it takes to reach 25–50 ppm nitrate. As long as the nitrate comes predominantly from the fertilizer and not from fish waste, then your plants will thrive. If you have 75 ppm nitrate or more, don’t stop fertilizing because fish waste is missing a lot of key elements like potassium. Use our water change flow chart to gradually lower the nitrate to 25 ppm or lower and then dose Easy Green as appropriate. For more information on nitrate and proper dosing for plants, read the full article.

2. Easy Root Tabs

While Easy Green is a liquid fertilizer absorbed by plants from the water column, heavy root feeders — such as sword plants, cryptocoryne plants, and bulb plants — prefer feeding from the ground. (Heavy root feeders still take some nutrients from the water column, so providing both liquid and ground fertilizers gives you the best growth.) Many hobbyists like using nutrient-rich substrates such as organic dirt or expensive aquarium soil, but be aware that they can come with side effects like lowering the pH or leaching ammonia into the water (which is toxic to fish). If you are using a cheap, inert substrate like regular aquarium gravel or if your aquarium soil has run out of nutrients over time, just add Easy Root Tabs to fertilize the ground.

Easy Root Tabs contain a mix of mineralized topsoil, high-quality red clay, and many essential nutrients (like nitrate, phosphate, potassium, and iron). Insert a capsule as deep as possible in the substrate using your fingers or tweezers in a grid pattern spanning every 4–6 inches. If the heavy root feeders are not evenly spread out in the tank, then place the root tabs directly under the plants. For example, a small crypt may need one root tab, while a giant Aponogeton plant may need seven. With liquid fertilization, we can test the water to see when to dose more, but for substrate fertilization, you have to regularly observe the heavy root feeders to see if they are melting away or showing other signs of nutrient deficiencies. See the article on root tabs for more details.

3. Easy Iron

If you are dabbling in red plants but aren’t getting the vivid scarlet hues that you see online, most likely you need to provide high lighting, perhaps add CO₂ injection, and then consider adding an iron supplement. The reason why Easy Iron is the only individual nutrient with its own separate bottle is because the formula for Easy Green is already saturated with iron. Plus, if Easy Green contains too much iron, it could potentially lead to algae problems, such as hair algae.

Iron is an essential element used by plants to make chlorophyll, which is particularly important for fast-growing or high light plants. Therefore, if you notice the newest leaves on your plants are yellow or pale-looking from a lack of chlorophyll but the leaf veins are still dark-colored, then try dosing some Easy Iron. To learn about specific dosing guidelines, read our article on iron supplements.

4. Easy Carbon

Fun fact: the liquid carbon products sold by aquarium companies — like Seachem Flourish Excel or API CO₂ Booster — are not actually fertilizers and serve as poor substitutes for CO₂ gas systems in planted tanks. Instead, these products usually contain glutaraldehyde, which is a fish- and invertebrate-safe algaecide commonly used to inhibit algae growth. Our version of liquid carbon is called Easy Carbon, and if you have a little algae, it is good for treating the entire aquarium to help minimize algae over time. You can also use a pipette for spot treatment of black beard algae and other hard-to-remove algae.

However, if the entire tank is heavily infested, dosing Easy Carbon may not improve the situation because the algae will grow back faster than you can kill it. In those cases, we recommend focusing on balancing the lighting, fertilizer, and CO₂ (if used) in the system to grow healthy plants that outcompete the algae. Liquid carbon is a good aid for treating the symptoms of an unbalanced tank but will not solve the root of the problem. Finally, don’t forget that liquid carbon can negatively affect more sensitive plants like mosses, vallisneria, anacharis, and Marimo moss balls so consider treating them a reduced amount. For more details, see the article about liquid carbon.

Our goal at Aquarium Co-Op is to make plant fertilization as uncomplicated as possible because we want to help people who have never kept plants or are struggling to keep them alive. Most hobbyists need Easy Green, and then get Easy Root Tabs if they have rooted plants. For high light tanks with red plants, Easy Iron can help. And if you have algae problems, try Easy Carbon. Check out the full Easy Fertilizer line to boost the growth of your planted aquarium.