The Simples Phosphate PO₄ Recipe

DIY fertilizer with phosphate for planted aquariums

In this article, we'll continue exploring the simplest ways to prepare DIY fertilizers and now talk about phosphate — an element that aquatic plant enthusiasts pay attention to secondarily.

Let me make a small clarification about what I mean by "second important element". Here I mean that phosphate often becomes the second element you'll pay attention to when buying fertilizers, selecting dosages, or conducting water analysis. Regarding the impact on plant growth, you can't say that there's a most important or unimportant element: the absence of even one necessary element can negatively affect plant growth. Usually the first element that gets attention is nitrate, and the next one is phosphate.

Moving to the recipe, its preparation is as simple as in the case of nitrate. If you've never been involved in preparing DIY fertilizers and aren't familiar with the process of making nitrate fertilizer , I recommend starting with that one, since this article will have fewer explanations.

Usually phosphate is added to the tank ten times less than nitrate, if we're talking about neutral substrate. So, if you add 7 ppm of nitrate per week, then phosphate should be given in the amount of 0.7 ppm, that is, in a ratio of 1 to 10 to nitrate. I don't advise relying on tests; it's better to observe the condition of the plants. After all, your eyes are the most reliable tool for assessing the plants' needs.

For preparing phosphate-containing fertilizer, monopotassium phosphate (KH₂PO₄) is most often used, since it is the most common and available reagent. In addition, it contains less potassium compared to other phosphorus-containing reagents. In most cases, I would recommend avoiding adding additional potassium if you're not sure of its necessity for your aquarium.

The already classic recipe looks as follows:

This recipe was developed so that 1 ml of solution increases the phosphate level by 0.05 ppm in a 100-liter aquarium.

And now, similar to the description in the article about DIY nitrate, you can create your own recipe using the form presented below:

That's how simply you created your second recipe. All that remains is to prepare it.

Keep going and you'll succeed 👍