How to Make DIY Root Tabs. Pros and Cons. Comparison

How to Make DIY Root Tabs. Pros and Cons. Comparison

If you’re new to the aquatic plant-growing hobby, then you’re probably at least heard of fertilizers (and root tabs in particular), even if you may not be all that familiar with them. Many aquatic plants derive most of their nutrients from the substrate (root-feeders) and root tabs give them the boost that they may otherwise lack.

Of course, we can buy root tabs. However, one benefit of root tabs is that you can make them on your own and it’s quite easy, so long as you have some empty gel caps and the necessary nutrients to combine the two. You can then place your own gel cap (root tabs) in the substrate for your plants to enjoy.

It’s really that simple, though you can get more complicated with it depending on what your aquatic plant life needs in order to thrive. There are also some caveats to making your own root tabs that you should be aware of so that you can avoid them at all costs. 

So long as you know what you’re putting together and you effectively place your tabs, the plants in your aquarium will thrive and thank you for it. 

What Do You Need to Make Root Tabs?

1. The simplest DIY root tab method (Osmocote)

The simplest DIY root tab method (Osmocote) - materialsTraditionally, you can make your own root tabs very easily with just two purchases (Links to Amazon to check the price):

  1. bottle of Osmocote plus. Smart Release Plant Food (or Dynamite. All Purpose Plant Food)
  2. a pack of empty gel tabs—preferably the 500 count, size 00. 

Note: Although Osmocote plus is probably the most popular choice we can also use some other products instead, for example, Dynamite. All Purpose Plant Food. Check below the comparison table between these two products and Flourish Tabs™.

There’s no need for any sort of high-tech, crazy, scientific measuring instrumentation. All you need is the caps, the Osmocote, and a bit of time to sit down and put them together. 

Once you have both in front of you, simply open each gel cap and fill it liberally with the tiny Osmocote balls and place the two gel cap pieces back together. 

The main reason why we use these gel caps is that they get sticky when exposed to moisture and they begin to dissolve within 5 minutes or even faster.

Lots of aquarists use this method successfully but …there is also a downside.

Warning: Osmocote is a terrestrial plant fertilizer. It was not designed for an aquatic environment! For example, its active Nitrogen – 15%, whereas, if we compare it with seachem root tabs, it is only 0.8. As we can see Osmocote fertilizer has a significantly higher concentration of some of the chemicals that are toxic to our animals but extremely beneficial to the plants.

Therefore, be very careful with these ones and monitor your water parameters for ammonia. Do not put too many DIY root plants made of Osmocote in the tank.

Tip #1: To reduce ammonia spikes, you need to dig them deep into the substrate. In addition, it will prevent them from floating up because of the air in the gel tabs.

Tip # 2: If you make holes in the gel tabs (with a needle) they will less likely to float as well. However, it should not be a big problem since they dissolve fast.

Osmocote DIY root tabs
Pros Cons
Cheap High concentration of nitrogen (ammonia)
Very easy to make Can float
Very powerful  

 2. More DIY freeze root tab method

DIY freeze root tab method - materialsThe main purpose of using the gel caps is just a delivery method. However, there is another way.

  1. bottle of Osmocote Plus. Smart Release Plant Food (or All Purpose Plant Food)
  2. Ice Cube Tray. 

The process of making DIY freeze root tabs looks like this:

  1. Fill the ice cube tray with fertilizer.
  2. Add distilled, RO, or aquarium water into the ice cube tray.
  3. Put it into the freezer.
  4. Once frozen you can push them into the substrate where you want.

Important: Once again, I need to remind you that these root tabs are powerful. So, if you over-doze them, you may have an adverse effect on your invertebrates.

DIY freeze root tabs
Pros Cons
Extremely cheap High concentration of nitrogen (ammonia)
Easy to make Takes time to prepare (freeze)
Easy to place Takes place in the freezer
Very powerful  

3. Complex DIY root tab method

There are other methods as well, although the above is the simplest. For a more customizable method, where you select the primary ingredients that you need for specific plants, you should try the clay version.

It’s a lot more time-consuming and is certainly messier but if you have particular aquatic plant life with specific needs, you’ll want to design something that may be outside of what a bottle of Osmocote offers.

Complex DIY clay root tab method - materialsHere is what you’ll need to get started:

  • Natural Clay
  • KN03 (Potassium Nitrate)
  • MgsO4 (Magnesium Sulfate Epsom salt)
  • K2SO4 (Potassium Citrate)
  • KH2PO4 (Potassium Chloride)
  • CASO4 (Calcium Sulfate)

Ideally, all these products should be 100% pure.

When you get started making these things, you’ll want to measure out some ratios with your nutrients. You’ll also need plenty of water to open the clay up enough to properly mix all of your ingredients.

  • 4 Tablespoons of KN03
  • 3 Tablespoons of MgsO4
  • 3 Teaspoons of K2SO4
  • 2 Tablespoons of KH2PO4
  • 1 Tablespoon of CASO4

The process of making DIY clay root tabs looks like this:

  1. Combine all of your ingredients.
  2. Flatten the piece of clay into a small circular shape (about 1/8″ or 3 mm thick).
  3. Take some of that mix and spread it all over the top layer of clay. (Not too much because we want it to go inside of the clay).
  4. Fold the clay.
  5. Mix it as thoroughly as possible.
  6. Once it is completely mixed, we have two options. 

Option # 1: Once it’s dry enough to where it’s very malleable, but not sticking to your hands any longer, you can roll it out, cut out your pieces, and start making your own little squares that are about ½” x ½”. 

Next, you can let them dry out under the sun or you can bake them for 10 minutes.

Now you can start placing your root tabs in your substrate. Clay root tabs don’t need to be buried as deeply as the gel tabs, but you still want to be able to push them down, roughly 3” into the substrate. 

Should I bake clay DIY root tabs or Not

Some people say that you should never bake (especially iron root tabs). They claim that plants can absorb only the Ferrous form of iron (Fe2+) and the Ferric form of iron (Fe3+) cannot be absorbed by them. Therefore, you bake them the ferrous form of iron will react with oxygen and turn into ferric form.

Well, this is not true.

According to the studies, plants absorb iron mostly in the form of Ferric ions. However, plants in acidic soil can absorb iron in ferrous as well as ferric form.

Therefore, for our goals, it really does not matter whether you bake root tabs or sundry.

Option # 2: You can dry the clay and powder it. After that, you can put this into gel capsules and use them as root tabs.

DIY Clay root tabs
Pros Cons
More balanced Require more ingredient
Do not float Require more time to make
Can be used in shallow substrates Cost a little bit more money but, still, cheaper than brand ones
Can be any shape and size you want Messy
No ammonia spikes  

How to Place Your Root Tabs

Depth and spacing are both important when it comes to placing your root tabs in the substrate. You don’t want to get too much concentrated in a small area and, more importantly, you don’t want to raise the ammonia levels to a point where it’s toxic.

If you don’t adequately bury your root tabs in the substrate, ammonia toxicity may become a real issue for your animals in the tank and you’ll do the exact opposite of what you intended to do. 

  • The clay, DIY root tabs should be buried at least 2 – 3” (5 – 7 cm) or even deeper into the substrate and 5” to 6” (12 – 15 cm) apart. You’re welcome to design your own grid, so long as you appropriately space them out. If you have a dense amount of plant life, you can drop the spacing to 4” (10 cm) Depth remains the same. 
  • With the gelcaps, the spacing is the same—depending on the density of your plant life in the aquarium.

However, you want to get deeper than 3” (7 cm) if possible. If your substrate is already very shallow, the DIY gelcaps probably aren’t your best bet and you should go with the clay.

Placing root tabs is always a messy thing. So, a pair of aquarium tweezers are the perfect tool for either the clay or gelcap DIY capsules, especially if you can find some tweezers that are much larger types.

Just grab the root tap with the end of the tweezers and push it down into the substrate to the appropriate depth. 

How to Store DIY Root Tabs

Personally, I recommend using plastic zipper bags to store gel caps. These bags will reduce the amount of moisture getting into it. Why it is so important?

Remember, when exposed to moisture and these caps begin to dissolve very fast!

Tip:  Unfortunately, unless you remove air from the bag, over time some moisture will get into the bag. So, use a desiccant silica packet that you find in all kinds of things (clothes, boots, toys, etc). Desiccant silica will keep your DIY root gel caps dry.

Comparison between DIY root tabs and Flourish Tabs

Active Ingredient


Dynamite. All Purpose Plant Food
Runs 15-5-9
Osmocote Plus


Flourish Tabs™
Nitrogen: 15% 15% 0.8%
Phosphate (P2O5): 5% 9% 0.11%
Potash (K20): 9% 12% 0.28%
Calcium: 2% 23.3%
Magnesium: 1.87% 1.3% 0.29%
Sulfur: 4% 6% 16.5%
Boron: 0.02% 0.02% 0.003%
Copper: 0.05% 0.05% 0.006%
Iron: 0.16% 0.46% 3.07%
Manganese: 0.05% 0.06% 0.16%
Molybdenum: 0.01%  0.02% 0.0005%
Zinc 0.05% 0.003%
Cobalt  0.002%

Frequently asked questions:

Are Osmocote or DIY root tabs shrimp safe?

Keep in mind that osmocote does contain copper ( around 0.024%) compared to standard root tabs.

Copper is something that any aquarist would like to avoid in their tanks. Luckily, the concentration is not high enough to harm even sensitive animals like dwarf shrimp.

Nonetheless, be reasonable, do not use lots of these root tabs in the shrimp tank and you will not have issues using it with shrimp.

How Long Do The DIY Root Tabs Last?

With the proper amount of nutrients, which you will get using the two methods above, you should get two to three months out of the root tabs from the moment you place them in the substrate

If you look up and a few months have passed by and you can see discoloration, strange spots, stunted or leggy growth, and the edges of the foliage starting to look a little worse for wear, it’s probably time to place your root tabs again.

For example, plants, such as the Amazon Sword, will curdle on the edges and start to lose their color somewhat. Of course, no one knows your plants better than you do and you will generally know when the plant life in your aquarium isn’t as robust as before. 

Once you replace your root tabs, you should see an exponential change in the vibrancy of your plants within just a few days. 

Related article:

I Have a nutrient-rich substrate, do I still need root tabs?

Nutrientrich substrates are usually used in planted tanks with heavy root feeders to provide continuously for a long time:

  • micronutrients (Iron, Boron, Manganese, Zinc, etc.) and
  • macronutrients (Nitrogen, Phosphorous, Potassium, Sulfur, Calcium, Magnesium). 

However, depending on the amount (depth) of substrate used, number and type of plants, water change schedules, CO2, and even lighting, nutrient-rich substrates start depleting their nutrient stores considerably after 6 to 12 months

Therefore, the substrate should be monitored and checked to see the signs of depletion. After that, you need to remineralize it with new root tabs on a regular basis or change the substrate.

So, yes, not right away but eventually, you will still have to solve the problem of substrate deterioration.

Do I need to place root tabs all over the tank?

No, you don’t. The great thing about root tabs is that you need to put them only near the plants you want to fertilize.

Where to plant root tabs?

If you need to fertilize only a few plants, you can place root tabs right under their roots (as close as possible).

However, if there are many plants, it is recommended to use the cross shape pattern (‘X’ shape) with one in the middle and four other root tabs on the end of the ‘X’.

How often should I use root tabs in the inert substrate?

The inert substrate is a substrate that does not change water chemistry (PH) and does not provide any nutritional value for the plants.

In the aquarium hobby, when we are talking about the inert substrate, we generally presume that these are sand and gravel. 

As for the answer, depending on the plant species, its size, and growth rate you will have to add root tabs once per 1-3 months.

For example, young and small plants do not absorb nutrients from root tabs very fast. Therefore, adding root tabs every 6-8 weeks will be perfectly fine. At the same time large and fast-growing plants consume way more nutrients, so they will require more frequent fertilization.

Related articles:

A few examples of heavy-root feeder plants

These plants get most of their nutrition from the soil. Therefore, eventually, they will need root tabs.

  1. Amazon sword,
  2. Cryptocoryne,
  3. Ludwigia repens,
  4. Red tiger lotus,
  5. Madagascar lace (Aponogeton madagascariensis),
  6. Marsilea hirsuta,
  7. Rotala Macrandra,
  8. Staurogyne repens,
  9. Glosso,
  10. Brazilian micro sword, etc.

In Conclusion

One of the best parts about DIY root tabs is that they are very inexpensive, easy to produce, and long-lasting.

You can make hundreds upon hundreds of the things and you can go two or three months before only having to use a handful in a single aquarium.

If you want to—or if you need to—you should definitely consider DIY root tabs for your aquarium plant life. You’ll get the robust and vibrant life that you’re looking for while avoiding any sort of serious drain on your wallet.

Related articles:

2 thoughts on “How to Make DIY Root Tabs. Pros and Cons. Comparison

  1. how big of a piece of clay do you use i see that it should be 1/8 ” thick but a weight or other dimensions would be helpful

    1. Hi John Beaudry,
      There is no need for that because it depends ONLY on how many DIY tabs I want to make.
      The most important part is that it should be big enough to ‘absorb’ all ingredients.
      This is normally a trial and error process, so expect it to take some adjusting to get it perfect.
      Best regards,

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