I was recently asked to write an article about custom micros. As some know I have been making my own now for quite a few years. I thought it was a good opportunity to try to take a complicated topic and make it easier to understand. Not sure if I succeeded or not. And thanks to my friends Vin Kutty and Joe Harvey who helped lend me a hand. To say I respect both of their thoughts is an understatement. They are two of the guys who are the reason that I got into the hobby. So here's what I came up. I hope it helps someone out there. And I am open to questions, compliments, criticisms or anything else you guys come up with.
Custom Micro Nutrients for the Planted Tank
What are custom Micro Nutrients?
Advanced aquarists have been making their own macro nutrient fertilizers for many years. Macros are the nutrients that plants need in large amounts. These include Nitrogen, Potassium, and Phosphate. Rather than purchase a premade mix, many purchase the individual dry salts and create their own custom blend.
In addition to macronutrients, plants also need micronutrients. These are nutrients that are required in very small or “trace” amounts. Until a few years ago, there were not many choices when it came to micronutrients. This has slowly been changing and there is new trend that has emerged: rather than purchasing premade mixes, many are now creating their own custom blend of DIY (Do It Yourself) micronutrients.
I first became aware of custom micros from my good friend Joe Harvey (2017 AGA Dutch 1st place). Joe and I have shared ideas on how we manage our planted tanks for many years. He explained that he had purchased the ingredients and was making his own custom micro mix. He asked if I wanted to go down this road with him. I am always looking for new ways to improve my tank and gladly said yes.
Why would someone want to create their own micronutrients?
Until recently, there have been limited options when it comes to micronutrients. You could purchase a premixed liquid solution, or you could purchase a dry mix like CSM + B. With larger tanks liquid solutions are not cost effective, and dry salts like CSM+B were not developed with the aquarium hobby in mind. It can have real issues with consistency when dosing in small amounts. With either you can’t change or adjust the ratios or the ingredients that they put into their formulas. When you make your own, you can custom tailor a solution to your own needs and be assured that the amount of every nutrient is the same in every dose.
As an example, let’s start with iron. There are several types of iron commonly found in micro mixes. These include Ferrous Gluconate, EDTA, and DTPA. They all have different chelating agents and work best at different pH levels.
Ferrous Gluconate is the easiest for plants to uptake and works best in low pH environments. It also has the weakest chelate, so it only remains available to plants for a short time. It is absorbed rapidly, like in hours. As you add stronger chelating agents, the iron is more stable and is released more slowly. For instance EDTA has a stronger chelate and will be available or a longer period of time. However keep in mind that it is most available at lower pH levels (below 6.5). DTPA has the strongest chelating agent and is best for tanks with a higher pH (6.5 to 8 pH). Many people don’t understand that the mix they purchase may not be providing the most effective source of iron for their tanks.
Other advantages of custom micronutrients are that they provide a lower average cost over time, the ability to customize the formula, and the confidence that each dose is consistent. And that consistency is one of the keys to success. In my experience, most micronutrients work best in a range. Too much or too little can have a harmful effect on a tank. When we create our own mix, we can be sure that we are always providing our preferred amounts.
What ingredients do you need to make your own custom Micro Nutrient Mix?
The first thing you will need to do is source the ingredients. Most of the components are sold in ½ or 1-pound bags. For most of these items that is enough for a lifetime supply! Remember we are using these to dose very small trace amounts. Here is a typical list of elements that go into a custom micro mix (Note: Some people consider Nickel to be optional). I’ve also listed the weekly ppm that I dose into my own tank. Over the course of many years I have experimented with various levels of each element. I’ve also compared those levels to others I know and respect in the hobby. All in all I have found this a good general starting point for most tanks.
The main component in a micro mix is Iron (Fe). As we discussed above you could use Ferrous Gluconate, EDTA, or DTPA. Which one works best for your tank depends on your tank’s pH level. Personally, I use both DTPA 11% and Ferrous Gluconate in my mix.
In addition to the elements, you will also need the following.
- 1000ml container
- Jeweler type gram scale (Minimum 0.01g accuracy)
- RO or distilled water
- Either distilled white vinegar or potassium sorbate (mold prevention).
When I first sourced everything above my initial investment was about $100.00. That’s lasted me about 5 years now and with many of the elements it is pretty much a lifetime supply. There are also kits you can buy from places like BurrAqua (
www.burraqua.com) if you don’t want to source everything yourself.
How do you make your own custom Micro Nutrient mix?
The next step is learning how to calculate how much of each item to add to your customized mix. Keep in mind that you are making a custom solution that is unique to your tank. The good news is it’s much easier than you think. There are planted tank calculators available that make the process very simple. You can use either RotalaButterfly (
Rotala Butterfly | Planted Aquarium Calculators & Information) or the Zorfox Planted Tank calculators (
Zorfox's Planted Tank Calculator). Once you understand how to use these tools, they will become one of your best friends as you advance in the hobby.
To use the calculators you will need to know your actual water volume, your container size (1000ml), the size of the dose you prefer, and how many ppm of each item you want to provide per dose. For instance in my tank my actual tank water volume is 105 gallons. I am using a 1000ml container for my solution. I dose 20ml of solution into my tank daily.
Let’s start with iron. I would like to dose 0.40 ppm of iron weekly, so that means I need to dose 0.0571 daily. When I enter these numbers into one of the calculators it will calculate that I need to add 10.32 gm of DTPA 11% to my 1000ml solution to provide 0.0571 ppm iron per 20 ml dose. Once you understand how to perform that calculation it’s easy to calculate the rest of the elements.
Here's how that calculation looks on Rotala Butterfly.
Here’s the actual recipe for my custom solution.
Once you have added the elements to the solution it’s a good idea to add a mold inhibitor. I use either 20 ml of distilled white vinegar or 0.4 gram potassium sorbate added to a 1,000ml container. I also recommend storing the container in a dark area like a closet, so it’s not subjected to sunlight.
How do I measure such small quantities of Cu, Mo, and Ni?
This is a question that comes up often. These three elements are needed in miniscule amounts. It is very difficult to measure these tiny amounts like 0.01 grams of Nickel accurately and consistently.
That is why I recommend creating a separate second 1000ml solution for these three minerals. You’re essentially making a super-concentrated solution of these three minerals instead of measuring teeny tiny amounts of powder. You then add some of the super concentrated solution to the primary solution (serial dilution). This will make your dosing more accurate and consistent.
Once you make your secondary solution, you add a little of the secondary solution to raise the ppm to the targets in our primary solution. It also saves a lot of time each time you need to make a new batch of micros. No more struggling to measure very small amounts of powder.
How do I make a secondary solution?
If you make a secondary solution, you will need two 1000ml containers.
The primary solution will contain Fe, B, Zn, and Mn.
The secondary solution wil contain Cu, Mo, and Ni.
In my case, I create my secondary solution and then add 60ml of it back to my primary solution.
My primary solution is enough for 50 days of dosing. But the 1000 ml of secondary solution will last for 800 days!
It’s a bit more work up front but saves lots of time in the long run. It also helps to make sure your mix is consistent and accurate.
I’ve been making my own custom micros for years now. I can tell you that once you have purchased everything and made the calculations it takes me less than 5 minutes to make a new batch. If you look at the effort and time we spend creating our underwater gardens, in my opinion making your own DIY micronutrients is relatively easy and well worth the effort.
