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? You could have a shortage of nutrients. Your plants may be lacking key building blocks, even if you regularly fertilize them. This article will teach you how to spot the signs of nutrient deficiency so you can prevent your plants from reaching death’s door.

Illustration of a healthy, normal-looking 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. Classic signs of nitrogen deficiency include old leaves turning yellow and translucent, especially starting at the leaf tips, as the plant consumes nutrients from its old leaves at the bottom in order to make new leaves at the top.

Signs that old leaves may have a nitrogen deficiency

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.

The same principle applies if you prune or remove a bunch of plants – make sure to lessen the amount of nitrogen provided. We recommend that you match the fertilizer that you use to your plants’ growth, whether it is liquid fertilizers that are used for plants that rely on the water column or root tabs that are used for plants that rely on their roots.

You may notice yellowish or translucent leaves in a newly added plant to your aquarium. This is not a sign that the plant has a 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 may even occur if you buy a submersed-grown plant from another hobbyist because the plant needs time to get accustomed to your tank’s different water parameters.

Stem plants that have lost their lower leaves due to melting tends to become bare, with no leaves above. After it has fully converted to only submersed-grown leaves, you can cut off the healthy-looking top and replant it so that you won’t see the skinny stems anymore. 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. On the other hand, older leaves are usually normal.

Signs of iron deficiency on new leaves

It can be difficult for iron to be incorporated in common fertilizers. So instead of buying more fertilizer that is all-in-one, consider purchasing an iron-specific product to treat your plants. Adding extra iron can also be used to enhance the color of red plants.

Potassium Deficiency

It is easy to identify this condition because the leaves of the plant will develop distinct pinholes, which are often rimmed in brown or yellow. Anubias and java fern thrive in areas with higher potassium levels, so be aware of these signs. You can buy a potassium-specific supplement, but we already fortify Easy Green with extra potassium to address such problems. Therefore, treatment can be a simple matter of just dosing more of our broad-spectrum fertilizer.

Signs of potassium deficiency in old leaves

Phosphate Deficiency

Another macronutrient that plants consume is phosphate, which is similar to nitrogen. 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. However, sometimes people will put phosphate-absorbing pads in their filters to prevent algae growth, and that ends up starving the plants of phosphate.

Signs that old leaves may have a phosphate deficiency

Magnesium Deficiency

A lack of magnesium is similar to an iron deficiency. In this instance, older leaves are affected. Sometimes, the edges of leaves may become droopy. Magnesium can be found in many general-purpose fertilizers. If you don’t have enough, consider adding it to your fertilization program. This condition can often be linked to calcium deficiency.

Signs of magnesium deficiency on old leaves

Calcium Deficiency

If you see new leaves growing in a twisted, gnarled fashion, this is usually related to a calcium or water hardness issue. Low water hardness is often a sign of calcium, magnesium, or manganese deficiency. You may need to supplement your water with special salts if you have soft water, RO/DI (reverse-osmosis deionized), or crystal shrimp. You can increase calcium levels gradually by using crushed coral as a filter or adding Wonder Shell to your aquarium.

Signs of calcium deficiency on 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). Make sure you are getting the right nutrients if you decide to add more fertilizer. Easy Green does not affect water hardness, calcium, or other levels.

You can solve most deficiencies by increasing your intake of all-in one fertilizers. For instance, if you are missing nitrogen, it is likely that you are also missing other nutrients. 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).

Simple Green is our recommended fertilizer. We originally developed it for use in our store, as we wanted a fertilizer that is easy to use without having to measure different supplements, higher in nutrient concentration, and reasonably priced. The all-in-one liquid fertilizer provides all the nutrients that aquatic plants need 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 of the experiment, you can adjust your fertilization schedule to reflect what the plants are actually eating. Plant aquariums are an ever-changing landscape. Your fertilizer requirements will change as your plants grow, the leaves are cut, and plants are removed or added to. You’ll have a beautiful and thriving aquarium if you take the time to inspect your plants and identify any nutritional deficiencies.

Get our infographic on plant nutrient deficiencies for quick reference here: