I started out using pre-mixed ferts as they are easily available and ready to be used. And financially, it does not make a big impact when you have just one tank.
However, when you progress in this hobby, you will most likely ended up with a handful of planted aquariums in your home. And as you gain more confident and interest in the hobby so does the size of your aquarium.
When you progress into multiple aquariums or into the territory of large aquarium like a 75 gallon, buying pre-mixed ferts becomes a financial burden. You will find yourself buying larger quantity of of ferts to enjoy more savings. But it will come to a point whereby buying in bulk will still hurt.
This is usually the signal for most to search for “How to dose dry ferts”.
There are literally thousands of very useful information online, mostly from forums. Again! No single place to give a direct instructions to simply follow. They all provided theories, methods, and explanation, but no simple instructions.
What you will need to buy
In a lot of countries Potassium Nitrate (KNO3) is a control substance and are not available as powder form to be sold openly. You may find some shops selling 5% KNO3 solution but I will show you how you can substitute KNO3 with Calcium Nitrate, which is much widely available.
Shopping List
| Potassium Sulphate | K2SO4 |
| Calcium Nitrate | Ca(NO3)2.4H2O |
| Potassium Dihydrogen phosphate | KH2PO4 |
| Epsom Salt/Magnesium Sulphate | MgSO4 |
| Seachem Flourish | Micro nutrients |
| EDTA Fe (13%)/DTPA (7%) | Fe |
| Seachem Flourish Iron | FE ferrous iron gluconate |
Apparatus
| Digital weighing scale | To measure the chemicals weight | Get it here> USD3.00 Free Shipping |
| Beaker | To measure water volume | Get it here> USD1.50 |
| 2x 600ml bottles | To contain the mixed ferts |
I will leave you to do your own reading about how the above chemicals will provide NPK and the micro nutrients.
Noted about FE dosing
If you can’t get your hands on FE in EDTA 13% or DTPA 7% form, you can just grab a bottle of Seachem Iron or other equivalent.
EDTA chelated 13% is meant for water with pH lower than 6. Water at more than pH 6 most of the iron will not be absorbed. Also it is best for soft water.
DTPA chelated 7% is best for water up to a pH value of 7.5. It is also less reactive with calcium rich water.
Where to buy
The chemicals can be found in any home gardening stores. These are common fertilisers used by gardening as well as hydroponics.
When buying online, please choose fertiliser grade. Lab or science grade can be very expensive.
Singapore Readers
For dry ferts you can get it online from ECO CITY. Click below to go directly to the links to the individual ferts
| Potassium Sulphate | Link |
| Calcium Nitrate | Link |
| Potassium Dihydrogen phosphate | Link |
| Epsom Salt/Magnesium Sulphate | Link |
For Epson Salt you can get it from any pharmacy.
For the bottles, I got it from Daiso! $2 each!
For the digital scale, you can get it from AliExpress just USD4 with free shipping!!! WTF?! In the US and can’t wait? Try Amazon USD8.
PPS Pro
There are again a lot of types of dosing methods but I will touch the PPS Pro for now. It is a leaner methods than EI methods.
Formular
You will need two bottles for the dry ferts. This is a draw back when you use Calcium Nitrate instead of Potassium Nitrate.
When you mix Potassium Sulfate and Calcium Nitrate there will be a chemical reaction which will result in a white precipitation (Calcium Sulphate). It is fine to dose into your aquarium but may be unsighty.
So you need to prepare a separate bottle for Calcium Nitrate.
Bottle #1
| Potassium Sulphate | K2SO4 | 29.3g |
| Potassium Dihydrogen Phosphate | KH2PO4 | 2.7g |
| Epsom Salt | MgSO4 | 19.2g |
| Distilled Water (tap water is fine) | H2O | 500ml |
Bottle #2
| Calcium Nitrate | Ca(NO3)2.4H2O | 36g |
| Distilled Water (tap water is fine) | H2O | 500ml |
Bottle #3
| EDTA Fe (13%) | DTPA Fe (7%) | DTPA Fe (10%) | 14.56g | 27g | 19g |
| Distilled Water (tap water is fine) | 500ml |
That’s it!
If you have a 10 gallon tank, each dose is 1ml. It will last you 16 months!
Dosing Amount
It is very simple. The base amount are as follows,
| Bottle #1 | Bottle #2 | Bottle #3 | Flourish | |
| 1 gallon | 0.1ml | 0.1ml | 0.1ml | 0.083ml |
Example, if you have a 75 gallon tank, then multiply 75 to the base amount. If you have a 5 gallon then just multiply the base amount by 5.
| Bottle #1 Daily | Bottle #2 Daily | Bottle #3 3 times per week | Flourish 3 times per week | |
| 5 gallon | 0.5ml | 0.5ml | 0.5ml | 0.42ml |
| 10 gallon | 1ml | 1ml | 1ml | 0.83ml |
| 55 gallon | 5.5ml | 5.5ml | 5.5ml | 4.57ml |
Dosing Frequency
| Bottle #1 (Macro) | Daily |
| Bottle #2 (Macro) | Daily |
| Bottle #3 (micro) | 3 times weekly (alternate with Micro) |
| Seachem Flourish (Micro) | 3 times weekly (alternate with Bottle #3) |
Dosing Adjustment
The PPS Pro is somewhat in the lean spectrum of dosing regimes. The standard dose amount is for lightly planted tank or for tank with low lighting.
If you have heavily planted tank please double the dosage for Macro. If you have medium or high lights please double or triple the dosage for Macro.
In essence, the PPS Pro is a lean EI dosing regime.
That’s it! Have fun!
Hi Chi Siang,
Thanks for writing up this detailed dry fert guide, been searching for a substitute for KNO3 as it is controlled in Singapore. I read that calcium would increase the GH of the tank. If I follow the dosage in your guide, would GH reach levels that would be detrimental to fish? Are there some species of fish that I should avoid using calcium nitrate dosing? Thank you.
Hi Chris
So far I have no problem with Calcium nor GH problem when using Calcium Nitrate. Singapore’s water is soft to begin with. The only problem I have, which is not a biggie, is the calcium residue/deposit at the water line when water evaporates. This requires a little more time cleaning it off.