In your mind’s eye, you imagine a planted aquarium. It’s full of lush, carpeting plant. There are tall stem plants all over the place with their tops poking out of water. Fish dart around the plants. Reality sets in as you gaze into the tank. The plant leaves is pale, especially on their ends. Maybe there are brown spots on them, almost like someone burned them.
If this happens to you, you’re not alone. Aquarists frequently see signs of nutrient deficiency in their plants. Yes, they can be sick. But more commonly, they signal that the plants lack what they need. Plants also exhibit their stress signals in ways that aren’t naturaly apparent. When you observe something amiss, it helps to know where you should of been. These symptoms divide into groups in the infographic above. Use it to go from guessing to diagnosis.
How to Fix Sick Aquarium Plants
Nutrients fall into three categories: micronutrients, secondary elements, and macronutrients. That grouping can be helpful for predicting what’s wrong, telling you what shows up first. Macronutrients are the big ones, which is the primary nutrients of N-P-K (nitrogen-phosphorous-potassium). These is used in huge amounts by plants as they create the structure of plant.
If there isn’t enough nitrogen, older leaves will go yellow. Why? Because the plant has taken the nutrients out of its own old tissues and put them toward growing new stuff. That’s not failure… It’s a survival tactic. Symptoms often show up in the wrong places for many hobbyists.
Mobile vs. Some nutrients is immobile (see chart). Nitrogen, potassium and other elements travels around the plant freely. In short supply, they will be relocated by the plant from older leaves down into newer ones at the top of the plant. Check your fertilizer amounts if you have dying leaves on bottom while those on top are fine.
Calcium and iron and other immobile elements don’t travel around the plant. If your newest leaves is all twisted/pale, you probably lack such elements in your current water supply. One familiar symptom is iron deficiency. The yellow tissue surrounds bright green veins like a map. The plant needs iron for chlorophyll production but can’t transport it into the new leaf.
The solution is to use chelated iron. Common iron drops will fall out of solution rapidy and particularly when pH is high. By keeping the iron bound by chelating agents, it remains available to be taken in across various water conditions. Chemistry at work for you.
Then there are the subtle players. Chlorophyll molecules contains magnesium at their core. No magnesium, no photosynthesis. If there isn’t enough magnesium in the tank, you may notice your older leaves turning yellow between the veins. This is similar than an iron deficiency but in a different spot. Adding epsom salt may help with magnesium deficiencies.
Potassium appears as holes in leaves or as browning around leaf edges. This regulate the flow of water within the cell. Leaf structure will fail under normal pressure when it lacks sufficient potassium. It’s not easy to diagnose. Nutrient deficiency can look like not enough light. Pale plants either have too little light or too little nitrogen.
Before fertilizing, test your water and check your PAR levels to follow the guide and avoid using too much fertilizer to fix poor light. When lights don’t match nutrients, algae occurs. Feeding is not just pouring liquid into the tank. Plants such as crypts, swords, etc., recieve slow release nutrients via root tabs in the substrate. Efficient uptake of nutrients requires plants to have CO2 injected. Excess nitrate and phosphate goes toward feeding algae rather than plants when there isn’t adequate carbon available.
A planted tank needs balance. It’s a closed system, so you control light, minerals, and carbon. Stop the guessing by learning to read your leaves. Pale old leaves means they want nitrogen. New tips with twists mean they need iron or calcium. Understand the signs, your tank will be green again, like a garden.
