# KH2PO4 helplessly lost



## zaggnot (Mar 8, 2006)

I’m sitting here racking by brain trying to figure out how much KNO3 and KH2PO4 I need to put in my tank. I have a 120 gal tank with no CO2 and about 2.3wpg. Per Chucks Planted Aquarium Calculator I think a good starting point is:

KNO3 = 5ppm
KH2PO4 = 20ppm

I am also going to add Florish iron and trace, but haven’t gotten that far yet. Please take into account I’m a 100% complete newb at plated aquariums. I have read a ton of info on the net and probably have learned just enough to be dangerous. I’ve worked out the amount of KNO3 and KH2PO4 I want to use for Potassium and Nitrate, but Phosphate is my real question. According to the calculator the amount of KH2PO4 I’m going to use will give me 18ppm Phosphate. The suggested is 1ppm. Is this a concern or am I just making it one. If any of this sounds off please let me know. Any suggestions would great too. Thanks.


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## plantbrain (Jan 23, 2004)

If the tank is non CO2, add about 1/2 teaspoon KNO3 once a week.
Add about 1/8 teaspoon KH2PO4 once a week.
NPK is now covered.

This assumes you have a fully planted tank that's doing reasonably well.
Pack the tank with plants.

Adding some GH booster (gregwatson.com) or seaChem Equilibrium at about 1/4-1/2 teaspoon once a week is enough.

Feed fish, add plenty of algae eaters, etc.
BTW, no water changes, only top off the tank.
Skip the dosing once a month and note plant health the following week. Add more if the plants wane, especially watch the fast growers, they will respond first.

Regards, 
Tom Barr


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## zaggnot (Mar 8, 2006)

Thanks Tom for your reply. Strait to the point just the way I like it. I realize Ferts are controversial, but boy it's hard for a new comer to find a place to start. Thanks again.


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## BryceM (Nov 6, 2005)

Zaggnot,

Just for fun, most people shoot for about 20 ppm NO3 and 2 ppm PO4 in their tanks. That means that if you have a slower-growing tank (non CO2) you need to add even less than this on a weekly basis, since it will build up over time if you dose highly and don't do WC's.

If you actually get up to 18 ppm PO4 I don't think you'll like it very much. That's quite a bit outside the range of normal. Some people report plenty of problems in the 10 ppm range.


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## Samsara (Mar 21, 2005)

zaggnot said:


> KH2PO4 = 20ppm


Excuse me but i think this value is too high. The "suggested tank target level" for KH2PO4 is 1 ppm

Best Regards


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