Nutrient Deficiencies: why your Aquarium Plants Are Dying


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. Even if you are regularly dosing fertilizers, your plants might still be missing key building blocks that prevent them from growing and thriving. 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

Types of Nutrient Deficiencies in Plants

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 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.

When stem plants are melting, they tend to lose the lower leaves. This leaves a bare bottom and new leaves on top. Once the stem has completely transformed to only submerged-grown leaves you can remove the top and replant it. 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 of iron deficiency in 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. To enhance the color of red-colored plants, you can add extra iron.

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. Although you can purchase a potassium-specific supplement to help with these issues, we fortify Easy Green with additional 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. 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 of phosphate deficiency on 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 edges of leaves may become droopy. 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. Note: this condition is often related to calcium deficiencies.

Signs of magnesium deficiency in old leaves

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. 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). If you choose to dose more fertilizer, make sure it has the nutrient you need. Easy Green, for example, doesn’t alter water hardness or calcium levels in any significant way.

Many deficiencies can be corrected by increasing the amount of all-in-1 fertilizers. This is because, if your plants are lacking nitrogen, then you may also be missing other nutrients. Your plants will soon run out of nutrients if you only give them a nitrogen supplement. Dosing Easy Green Tabs or Easy Root Tabs gives your plants more of the micronutrients and macronutrients they need (in the right amounts).

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. 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 takes about two to three weeks to notice a difference in the plants. Then you can assess if your actions made a difference. Based on the results of the experiment, you can adjust your fertilization schedule to reflect what the plants are actually eating. Because plants change over time, fertilizer requirements can change. Plants grow and are pruned. 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: