Nutrient Deficiencies: Why Your Aquarium Plants Are Dying

You have the perfect aquarium, but your plants keep dying. You could have a shortage 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.

Illustration of a healthy, normal-looking leaf

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

You may also run into nitrogen deficiencies if you don’t follow the recommended fertilizer dosage instructions. However, four months later, when your plants are three times their size, you still need to do 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. It is a good idea to match the amount you apply to fertilizer (whether it be liquid fertilizers for plants who feed from the water column, or root tabs for those plants who feed from their roots), with the growth of your plants.

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.

When stem plants are melting, they tend to lose the lower leaves. This leaves a bare bottom and 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 plants, and stem plants are notorious for melting in new environments, whereas anubias and java fern are pretty hardy in comparison.

Iron Deficiency

Plants that lack iron display yellowing or paleness on their newest leaves with leaf veins that remain darker in color. Older leaves look more 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. To enhance the color of red-colored plants, you can add extra iron.

Potassium Deficiency

This condition is easy to diagnose because the plant’s leaves will develop distinctive pinholes that are sometimes rimmed with brown or yellow. Anubias and java fern thrive in areas with higher potassium levels, so be aware of these signs. There are many options for potassium-specific supplements, but Easy Green already has extra potassium. Therefore, treatment can be a simple matter of just dosing more of our broad-spectrum fertilizer.

Signs of potassium deficiency on old leaves

Phosphate Deficiency

Another macronutrient that plants consume is phosphate, which is similar to nitrogen. Older leaves are more affected, and they will develop yellow spots with brown spots. As the leaves begin to die, green spots may form. This condition is more uncommon, since fish foods like flakes contain phosphates. To prevent algae growth, some people may use phosphate-absorbing pads to their filters. This can lead to the plants being starved of phosphate.

Signs that old leaves may have a phosphate deficiency

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 typically included in most general-purpose fertilizers, so dose more of it as part of your fertilization routine or consider using a magnesium supplement or Epsom salts to supply this nutrient. This condition can often be linked to calcium deficiency.

Signs that old leaves may have magnesium deficiencies

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. If you have soft water or are using RO/DI (reverse osmosis de-ionized) water for your discus or crystal shrimp, you may need to add these minerals using special salts to keep your plants healthy. You can also slowly increase calcium levels and hardness by adding crushed coral to the substrate or filter, Wonder Shell to the aquarium, or Seachem Equilibrium minerals.

Signs that new leaves may have calcium deficiencies

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). If you choose to dose more fertilizer, make sure it has the nutrient you need. 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. However, dosing more Easy Green or Easy Root Tabs provides more of the macronutrients and micronutrients your plants need (and at all the right concentrations).

Simple Green is our recommended fertilizer. 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. This all-in-one liquid fertilizer contains all the essential nutrients your aquatic plants need to thrive so that you don’t have to figure it out yourself. 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 these results, adjust your fertilization schedule so that it matches what the plants actually eat. 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. If you want your planted aquarium to thrive, make sure you regularly inspect it and spot any deficiencies.

Our infographic to help you identify nutrient deficiency in plants is a quick reference guide.