Nutrient Deficiencies: Why Your Aquarium Plants Are Dying

Do you have the perfect planted aquarium setup, but your plants are still dying one by one? It could be from a lack of nutrients. Your plants may be lacking key building blocks, even if you regularly fertilize them. We will show you how to identify the signs of nutritional deficiencies and help you take preventative measures to ensure your plants don’t die.

Example of a normal, healthy plant leaf

Different types of plant nutrient deficiencies

Nitrogen Deficiency

Low nitrates are a common problem in planted tanks, especially with beginners in the aquarium hobby who have been taught to do routine water changes every week (without testing for the actual nitrate level). This habit, while fine for fish only tanks, can lead to a lack of nitrogen, even if you are regularly dosing fertilizers. Old leaves that turn yellow or translucent are classic signs of a nitrogen deficiency. This happens because the plant uses nutrients from its bottom leaves to make new ones.

Signs of nitrogen deficiency on old leaves

A second reason you might run into nitrogen deficiency could be that you are following the recommended fertilizer dose instructions but the plants grow to three times the size of their original size four months later. You still need to apply the same amount. Just as you automatically feed more food if you add more fish to an aquarium or if they grow bigger over time, you need to feed your plants more as they get taller or propagate.

This principle is also applicable if you prune or take out a lot of plants. However, make sure that the fertilizer used is less. Our recommendation is to try and match the amount of fertilizer you use (whether it’s liquid fertilizers for plants that feed from the water column or root tabs for plants that feed from their roots) with your plants’ growth.

Now, if you see yellow or translucent leaves on a brand-new plant that was recently added to your aquarium, this may be a sign of melting, not nitrogen deficiency. Most plants that you buy online or locally were raised in water. Emersed (or out of water) leaves can melt and make room for submerged-grown or underwater-grown leaves. This melting effect can occur even if the plant is purchased from another hobbyist.

For example, stem plants that are melting tend to lose their lower leaves, leaving a bare stem on bottom with new leaves on top. You can trim the healthy-looking top off your stem plant once it is fully grown to submerged-grown foliage. Then, replant the stem so you don’t see any skinny stems. Amazon swords, cryptocoryne and stem plants are well-known for melting in new environments. Java fern and anubias are, however, quite hardy.

Iron Deficiency

Plants without iron show yellowing or pallor on their newest leaves. Leaf veins that remain darker in colour are a sign of iron deficiency. The older leaves, on the other hand, usually look normal.

Signs that new leaves have iron deficiency

It is difficult to incorporate high concentrations of iron in typical fertilizers, so instead of dosing more all-in-one liquid fertilizer, buy an iron-specific supplement to treat your plants. Adding extra iron can also be used to enhance the color of red plants.

Potassium Deficiency

The pinholes on the plant’s leaves can be easily identified. They may sometimes have yellow or brown edges. Certain plants like java fern and anubias thrive in environments with more potassium, so watch out for those signs. There are many options for potassium-specific supplements, but Easy Green already has extra potassium. Treatment can be as simple as adding more of our broad spectrum fertilizer.

Signs that old leaves may have potassium deficiencies

Phosphate Deficiency

Phosphate is another macronutrient like nitrogen that plants consume in large quantities. The older leaves will be most affected. They will turn yellow and develop soggy brown spots. Green spots of algae may also form as they begin to break down the dying leaves. This condition is more uncommon, since fish foods like flakes contain phosphates. Sometimes, however, people will use phosphate absorb pads in their filters to stop algae growth. This causes the plants to become starved.

Signs a phosphate deficiency in old leaves

Magnesium Deficiency

Lack of magnesium looks similar to a lack of iron, where leaves turn lighter in color with dark veins, but in this case, the deficiency affects older leaves instead new ones. Sometimes the leaf edges may droop as well. Magnesium is a common ingredient in general-purpose fertilizers. You can either add more magnesium to your fertilization regimen or use Epsom salts or a magnesium supplement to get this nutrient. This condition can often be linked to calcium deficiency.

Signs that old leaves may have magnesium deficiencies

Calcium Deficiency

You may notice new leaves becoming twisted or gnarled if you have a calcium issue. In fact, calcium, magnesium, and manganese deficiencies often coincide with low water hardness. These minerals may be required to maintain the health of your crystal shrimp or discus if you have soft or RO/DI water. You can also gradually increase calcium levels and water hardness by putting crushed coral in the substrate or filter, adding Wonder Shell into the aquarium, or dosing Seachem Equilibrium minerals.

Signs of calcium deficiency in new leaves

How to Fix Nutrient Deficiencies

In order to properly treat your plants, identify the nutrient deficiency and how you’re going to fix it (e.g., add more fertilizer or specific supplements, increase the water hardness, feed more fish food, and/or remove some plants). You should ensure that the fertilizer you use has the correct nutrient. Easy Green, for example, doesn’t alter water hardness or calcium levels in any significant way.

Most deficiencies can be solved by increasing your dosage of all-in-one fertilizers because if you’re missing nitrogen, for instance, you’re likely missing other nutrients as well. Your plants will soon run out of nutrients if you only give them a nitrogen supplement. Easy Green Tabs and Easy Root Tabs provide more of the macronutrients that your plants require (in all the correct concentrations).

EasyGreen is the best choice for aquarium plants. This fertilizer was initially developed for use in our retail store. It is easier to use than other supplements, has a higher nutrient concentration and is affordable. Easy Green is a liquid fertilizer that contains all the nutrients your aquatic plants require to thrive. Unlike other ammonia-based fertilizers, Easy Green is completely safe to use with fish, shrimp, snails, and other invertebrates.

It usually takes between two and three weeks for your plants to show a change. Once you do, you can determine whether your actions have helped or hurt them. Based on the results, tune your fertilization schedule to match what the plants actually consume. Planted aquariums are an ever-evolving landscape with fertilizer needs that must change as plants grow over time, leaves are pruned, and plants are added or removed. If you want your planted aquarium to thrive, make sure you regularly inspect it and spot any deficiencies.

For a quick reference guide, get our free infographic to plant nutrient deficiencies here: