Joined: May 01, 2008 Posts: 1100 Location: Lucknow
Posted: Wed May 04, 2011 9:23 pm Post subject: About How much to Dose KNO3 and K2SO4.
Until now I had been dosing my 56 gallon tank with 5 ml of K2HPO4, 20ml each of KNO3 and K2SO4 (40 gms dissolved in 1/2lt soln) thrice a week. But now just consulted Chuck Gadd's Dosage Calculator which gives the following result.
1. If I mix 100 gm of KNO3 in 500ml. of water, each ml. will add 0.58 ppm of NO3- to my tank.
Target Level is 5 ppm
So I need to add approx. 8.6 ml of this soln. to my tank every alternate day.
2. The same concn. of KNO3 will add .37 ppm of K+ per ml. to my tank.
So 8.6 ml. of this soln. will add approx. 3 ppm of K+ to my tank.
Target is 20 ppm. So I need 17 ppm more from K2SO4.
Now if I dissolve 50 gm of K2SO4 in 500 ml. of water, its each ml. will add .21 ppm of K+ to my tank.
So to achieve the remaining 17 ppm, I'll have to add 81ml. of K2SO4 to my tank every alternate day.
This result somewhat confuses me. Do I need to add that much amount of K2SO4 to my tank.
What happens to the SO4--, do the plants use that also or it just keeps on accumulating in the tank.
Last edited by saurabh_m on Thu May 05, 2011 11:00 am; edited 2 times in total
Joined: Jun 29, 2003 Posts: 7085 Location: Bengaluru, India
Posted: Wed May 04, 2011 10:42 pm Post subject: Re: About How much to Dose KNO3 and K2SO4.
Use Chuck's Calculator as a guide, and dry dose for EI. If not dry dose for an intermediate level between 5 ppm - 25 ppm for nitrates.
That will increase KNO3 dosage, provide more K from KNO3 and also from K2HPO4.
Then adjust K with K2SO4. The S in K2SO4 is needed by plants and will be used.
When you shoot for EI levels and carry out regular water changes weekly/fortnightly/monthly it does not matter,
You'll never exceed 2 x what levels you are trying to get with EI.
This 2x level is perfectly safe for plants and fish and will not be reached even if you have no plants in the tank.
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