KN03

[rossi32s]

If i am dsoing prilled KNO3 and paying attention to the nitrate levels should I assume that my Potasium levels will be in the range needed?

KNO3 - Potassium Nitrate K - Potassium 38.7%
NO3 - Nitrate 61.3%


THanks
Scott

[Perrush]

No.

K can be dosed by K2SO4

[Wasserpest]

From what I have read, the Potassium provided by KNO3 is not enough to reach the "optimum" 20 ppm level. Also, when you get a higher fish load, you will dose less NO3, but still need the same amount of K.

Having said that... If your plants look healthy and you don't have other (algae?) problems, I would hold off with K2SO4.

If you start to see holes developing in older leaves (in swords, for example) you might want to start looking for K2SO4.

[rossi32s]

since i am starting to dose from dry ferts... how do i test for Potassium?

I read that potasium is not a danger fert so is there a rule of thumb for dosing it?

Scott

[KyleT]

http://www.csd.net/~cgadd/aqua/art_p...osage_calc.htm

Scott if you click on that link it will tell you how much to dose for your size tank. There really is no need to test for potassium because it really isn't very lethal until you get to obsurd concentrations.

The easiest way to get some is to go to your local garden store and ask for "Muriate of Potash". Almost every garden store carries it, it is pure K20.

Kyle

[Wasserpest]

You can't really test for Potassium. Just take Chucks calculator, plug in 1 ml water, your tank size, and then play around with the teaspoons and see how many you need to get to 20 ppm.

After a gradual initial addition to bring it up to that level you will be dosing just for the water that you change.

[newtankgirl]

Originally Posted by Wasserpest

You can't really test for Potassium. Just take Chucks calculator, plug in 1 ml water, your tank size, and then play around with the teaspoons and see how many you need to get to 20 ppm.

After a gradual initial addition to bring it up to that level you will be dosing just for the water that you change.

I'm really confused now. On Chuck's site it says "this is the total level you should target for the tank. For nutrients like Potassium and magnesium, I add enough so that each week, I'm adding close to this amount." I was assuming that you start from scratch each week - so that in my 50 gal tank, for instance, I would add around a teaspoon of K2SO4 every week, which would add around 15 ppm of potassium. Which is correct? Do you add enough for the whole tank each week, or just enough for the water you're replacing? If you just add enough for the water you're replacing, that seems to suggest that your plants aren't using up what you put in the tank the week before.

[Wasserpest]

For potassium, you don't dose for the whole tank each week. That would lead to a steady increase of chemicals in your tank. You can not assume that the plants take up all the nutrients supplied, and since you can't measure it, to be on the safe side you only add enough to bring the replacement water to the desired level.

For NO3 (KNO3-dosing) you should monitor and dose according to your tank level. Fish poop and decaying plants all add to the NO3 level.
For example, if your test kit says 0, you should dose for the entire tank, to bring it to 5 ppm. But you need to be careful and do this gradually, since sudden changes in water chemistry can be harmful for your fishies. Plus the testkits I tried are not very precise in lower levels, between 0 and 10 ppm.