Selecting the Right Aquarium Plant Fertilizer – PART I

Selecting the Right Aquarium Plant Fertilizer – PART I

Published by Green Thumb Weirdos on Aug 21st 2021

If you are in the market for a plant fertilizer for your aquascape or planted tank, it is best to realize that what you are actually looking for is an aquarium plant fertilizer system. There are at least several systems regularly touted and, in this multi-part article, we will look at them all and weigh the pros and cons of each.

So many aquarium fertilizer products on the market today with catchy product names, flashy labeling and promises of ease of use have failed to deliver consistent results, often resulting in a nutritionally unbalanced aquarium filled with either algae or sick plants. This article is meant to help guide you through making an informed decision so you can find success the first time around!

All-In-One aquarium fertilizers have an advantage when it comes to ease of use and application. In these Aquarium Plant Fertilizers, the Macro-Nutrients necessary for plant growth (Nitrogen, Phosphorus, Potassium) are combined with vital Micro-Nutrients (copper, iron, manganese, chlorine, molybdenum, sulfur, zinc, etc.). These nutrients are dissolved and suspended in water and sold in a bottle, ready for use, and every time you dose, you are adding everything necessary for optimum plant growth. This sounds efficient, but it comes with a huge disadvantage, and one that often leads to problems.

Fertilizers that combine Macro and Micro-Nutrients together into a single liquid product (“All-In-One’s”) don’t allow for the reduction or increase of Nitrogen (N) or Phosphorus (P) independently. This is a MASSIVE problem, because Nitrogen and Phosphorus must regularly be dialed up or down depending on many factors like plant load, plant type, lighting levels, CO2 availability and so on. So how does one dial up or dial down Nitrogen and Phosphorus in an All-In-One fertilizer? The only way to do it is to increase everything or decrease everything because all your nutrients are combined. This is a terrible idea!

An excess of either Nitrogen or Phosphorus often results in an algae bloom, while too little Nitrogen or Phosphorus results in little or no plant growth, which indirectly leads to problems with unwanted algae growth too. But this isn’t all we are playing with when we are using an All-In-One fertilizer and we find ourselves decreasing or increasing dosing to move Nitrogen and Phosphorus up and down.

Too much iron, which is almost guaranteed if you are trying to “dial-up” with an All-In-One product, will cause leaf deformities and in very high overdosing scenarios, can cause plant death. However, iron is essential to photosynthesis, and without enough iron, plants enter a state known as “chlorosis” which is somewhat equivalent to a human medical condition known as “Anemia”. When we humans experience Anemia, we are weak because our body cannot product enough red blood cells. Red blood cells contain hemoglobin which carries oxygen to our cells. In plants, chlorosis is much the same – plants are pale green instead of vibrant and weak because they cannot feed themselves by way of photosynthesis.

So in very low-demand planted tank or nano-tank situation, an All-In-One fertilizer might be appropriate, but in almost all other scenarios, they are often the cause for either poor plant growth or unwanted algae outbreaks. But not to fear! In Part II of this article, we will look at another option that some feel is far superior, and others say is risky and overly complicated: ESTIMATIVE INDEX