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Discussion Starter · #1 ·
I am not sure how useful it may be, but still decided to describe my nutrients ratios for a successful Dutch tank. I am too lazy to change water weekly. My tap water is not good, so I use de-ionizing resins or buy distilled water at a supermarket. I only change 30-50% of water monthly or even once in two months, otherwise I would have to spent a fortune on resins. Then I add nutrients to achieve the desired ppm(s), presuming that the added water was distilled water - had no nutrients.

The desired concentration that I try to keep:
10 ppm Nitrogen,
2 ppm Phosphorus,
14 ppm Potassium,
21 ppm Sodium,
15 ppm Calcium,
5ppm Magnesium.

Ca and Mg will produce dGH of 3.25.
If you add both Na and K as hydro-carbonates (see below), they will produce dKH of 3.6, so at pH around 6.5 you will have plenty of dissolved CO2.

Nitrogen: 0.062g KNO3
Phosphorus: 0.053g KH2PO4
Potassium: 0.097 g KHCO3 or 0.072 g KCl
Sodium: 0.138 g NaHCO3 or 0.096 mg NaCl
Calcium: 0.139 g CaCl2*2H2O
Magnesium: 0.383 g MgSO4*7H2O or 0.317 g MgCl2*6H2O

For example, if you have a 41 gallons tank (4.1*10 gallons):
To achieve 10 ppm of N, add 10*0.062*4.1= 2.54g of KNO3
To achieve 2 ppm of P, add 2*0.053*4.1= 0.435g of KH2PO4
To achieve 14 ppm of K, add 14*0.097*4.1= 5.56 g of KHCO3 or 14*0.072g*4.1= 4.1 g of KCl
To achieve 21 ppm of Na, add 21*0.138*4.1= 11.9 g of NaHCO3 or 21*0.096*4.1= 8.3 g of NaCl
To achieve 15 ppm of Ca, add 15*0.139*4.1= 8.5g of CaCl2*2H2O
To achieve 5 ppm of Mg, add 5*0.383*4.1= 7.9 g of MgSO4*7H2O or 5*0.317*4.1= 6.5 g of MgCl2*6H2O

Sources of chemicals.
KNO3 - potassium nitrate, approx. $15/4 lb
KH2PO4 - Potassium Phosphate Monobasic, approx. $12/8 oz
KHCO3 - Potassium Bicarbonate, approx. $9/ lb
CaCl2*2H2O - Calcium Chloride Flake Dihydrate - $15/5 lb
NaHCO3 - Sodium Bicarbonate - baking soda
NaCl - table salt
MgSO4*7H2O - Epson salt, any pharmacy

ALWAYS dissolve EACH salt SEPARATELY before adding to the tank.

What if you do not have a good scales and need to add 0.435g of KH2PO4?

You can buy a variety of graduated cylinders and backers on Amazon. Do not save and buy plastic, glass is much better, easier to clean and longer-living. Most people have cheap kitchen scales to measure with 0.5g precision.
So you can prepare a solution of 43.5 grams of Phosphate in one liter = 1000 ml. Now you have 0.435g in 10 ml and can easily measure it in your aquarium. The rest of the solution will store forever in a closed bottle, to be used as needed!

Other info:
To add 0.5dKH to 41 gallons use: 2.77g KHCO3 or 2.32g NaHCO3.
This will increase your pH. If you add CO2, the pH increase will be very short-lived. If you do not add CO2, add slowly and in portions, so that the tank have time to absorb CO2 from the air.

Of course, K and Mg will be used up by your plants, so you need to add a bit extra depending on the amount of plants. I just do it by “feel”.

I feed only by blood-worms (buy the smallest for my cardinals). Usually the Nitrates are provided by fish poop. I usually need to add 1 ppm of Phosphate twice a week.

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I personally draw a lot of attention to these aspects and life is radically changing for the better. I started to pay attention to what I eat and to my way of life and I noticed many mistakes I made. I am proud that I managed to correct those mistakes. I started to eat properly and a huge influence in my change had the products from that I use so far. If you want a change, then it will really help you.
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