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. Even if your plants are receiving regular fertilizers, they might be missing essential building blocks that hinder their growth and thrive. This article will teach you how to spot the signs of nutrient deficiency so you can prevent your plants from reaching death’s door.

A healthy leaf of a normal plant.

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. The classic sign of a nitrogen deficit is yellowing and translucent leaves, especially at the tips. This happens when the plant takes nutrients from the bottom to make new leaves.

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. 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 purchased online or locally were grown emersed or out of water, and these emersed-grown leaves will melt away to make room for new, submersed-grown (or underwater-grown) leaves that look smaller and healthier. 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.

For example, stem plants that are melting tend to lose their lower leaves, leaving a bare stem on bottom with new leaves on top. 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 plants, and stem plants are notorious for melting in new environments, whereas anubias and java fern are pretty hardy in comparison.

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

High iron concentrations can be difficult to include in standard fertilizers. Instead of using more liquid fertilizer, you can buy an iron-specific supplement. You can also add iron to red plants.

Potassium Deficiency

The pinholes on the plant’s leaves can be easily identified. They may sometimes have yellow or brown edges. 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. It is easy to simply add more of our broad-spectrum fertiliser.

Signs of potassium deficiency in old leaves

Phosphate Deficiency

Plants also consume phosphate in large amounts. The older leaves will be most affected. They will turn yellow and develop soggy brown spots. As the leaves begin to die, green spots may form. 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 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 leaf edges can droop. 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 is often due to calcium deficiencies.

Signs that old leaves may have magnesium deficiencies

Calcium Deficiency

New leaves that grow in a twisty, gnarled manner are usually indicative of a calcium or hardness problem. Low water hardness can often lead to deficiencies in calcium, magnesium and manganese. 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 increase calcium levels gradually by using crushed coral as a filter or adding Wonder Shell to your aquarium.

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).

If you only get one fertilizer for your aquarium plants, we recommend Easy Green. 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.

Generally, it takes at least two to three weeks to see a difference in your plants and determine if your actions helped or hurt the situation. Based on the results of the experiment, you can adjust your fertilization schedule to reflect what the plants are actually eating. 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. 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: