# Question about DIY fertilizer (Estimate index)



## dan1619889 (Feb 27, 2012)

Hi, I'm going to start using fertilizers (Estimate Index) in my 19 gallons, but I have only found K2SO4 and KNO3, and can't find KH2PO4.

I have used a fertilizer calculator and I should add:

K2SO4 (20ml per week) *Mix : (500 ml + 40g K2SO4)*
KNO3 (30ml per week) *Mix: (500 ml + 40g KNO3)*
KH2PO4 (10ml per week) *Mix: (500 ml + 15 g KH2PO4)*

These values give me: nitrate (21 ppm), *phosphate (3ppm)*, potassium (22 ppm)

Can I use only the two I have, or Phosphate (KH2PO4) is a must? In that case, How can I replace it? I have searched all my city and found nothing (I'm from Ecuador).

Thanxs&#8230;!


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## rjordan393 (Nov 23, 2012)

You can purchase KH2PO4 at aquariumfertilizers.com
How did you determine the levels for nitrate, phosphate and potassium? You should strive for a 10 to 1 ratio of nitrate to phosphate. 10 ppm of nitrate and 1 ppm of Phosphate. Your potassim is slightly high and I would recommend 10 to 15 ppm.
When you make up your fertilizer solutions, keep in mind that you will be dealing with the production and uptake of nitrate and phosphate from the fish and food. Only experience will tell you just how many times to dose and the amount to dose.
For instance; there is a product called "Equalibrium" by Seachem and it used for raising the general hardness and it contains about 23% potassium. I find that 2 level teaspoons in 27 gallons of water will raise the Potassium level in my makeup water to about 10 ppm. So you need to check your towns water analysis report for potassium. They are usually available on the web. Then you must adjust for whats in your water and the strength of the solution to reach 10 to 15 ppm potassium. Do this for nitrate and phosphate if necessary.


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## Yo-han (Oct 15, 2010)

You need K, NO3 and PO4 for EI. Most K comes from KNO3 but adding extra is no problem because it can be dosed quite high before coming lethal. But you will need a PO4 salt. Most PO4 salts are insoluble in water, but maybe you can find Na3PO4 (sodium phosphate). Potassium phosphate is better because the sodium is not used by plants, but if you really can't find it, maybe this will work


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## dan1619889 (Feb 27, 2012)

rjordan393 said:


> You can purchase KH2PO4 at aquariumfertilizers.com
> How did you determine the levels for nitrate, phosphate and potassium? You should strive for a 10 to 1 ratio of nitrate to phosphate. 10 ppm of nitrate and 1 ppm of Phosphate. Your potassim is slightly high and I would recommend 10 to 15 ppm.
> When you make up your fertilizer solutions, keep in mind that you will be dealing with the production and uptake of nitrate and phosphate from the fish and food. Only experience will tell you just how many times to dose and the amount to dose.
> For instance; there is a product called "Equalibrium" by Seachem and it used for raising the general hardness and it contains about 23% potassium. I find that 2 level teaspoons in 27 gallons of water will raise the Potassium level in my makeup water to about 10 ppm. So you need to check your towns water analysis report for potassium. They are usually available on the web. Then you must adjust for whats in your water and the strength of the solution to reach 10 to 15 ppm potassium. Do this for nitrate and phosphate if necessary.


Hi, thanx for the info...! I have used a calculator ("Calculadora mundo vegetal" all the credit is for the author).

1.- Introduce the liters of the aquarium

2.- The solution you are going to use, so I used: 500 ml H2O2 + 40g KNO3, and then, how many ml are you going to introduce in your aquarium, I used 30 ml

3.- It gives you the ppm you are giving the aquarium.

If this is correct, I'll be adding nitrate (21 ppm), phosphate (3ppm), potassium (24 ppm) weekly


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## farrenator (Dec 21, 2008)

Sodium phosphate and sodium bi-phosphate are commonly found in enema solutions that are readily available in pharmacies. For example, 'Fleet Enema' - http://www.drugs.com/mtm/fleet-enema.html

Check your local pharmacy for enema solutions used to treat constipation.



Yo-han said:


> You need K, NO3 and PO4 for EI. Most K comes from KNO3 but adding extra is no problem because it can be dosed quite high before coming lethal. But you will need a PO4 salt. Most PO4 salts are insoluble in water, but maybe you can find Na3PO4 (sodium phosphate). Potassium phosphate is better because the sodium is not used by plants, but if you really can't find it, maybe this will work


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## rjordan393 (Nov 23, 2012)

If you dose according to the recommened amount as per the graph, it still does not account for the nutrients produced by left over food or by what the fish produce. You cannot count on the plants to absorb it all. In well maintain tanks by aquarists who know how much to feed without going overboard only comes through experience. I recommend you do a search on the "Redfield Ratio" and follow it. You can always increase your dosage if required. 
On forums that deal with fish and plants, you may see that there must be a balance between light & fertilizer for success. Too much of any nutrient can interfere with the uptake of another nutrient.
You say you have a 19 gallon tank and the ppm you have from the graph in my opinion is not accurate. In my own 75 gallon tank, I maintain 10 ppm nitrate and 1 ppm phosphate and keep the potassium at least 15 ppm and my fish and plants are doing well.


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