A little twist on an old subject....blended nitrates

Lousybreed · May 4, 2020

I am wondering if there would be any solubility issues if you were to make a 50:50 blend of KNO3 and NaNO3 to reduce the amount of K I am putting in my system. Looking at their high solubilities in water I am assuming there won’t be any problems but wanted to see what others thought.

JimWelsh · May 5, 2020

Well, you don't indicate how many grams per liter of each you intend to try to dissolve, and that matters, but I agree that both are quite soluble. Sodium nitrate is the least soluble of the two, at 730 g per liter, so as long as your combined total weight is well under that (which I'm sure it will be) then knock yourself out.

Randy Holmes-Farley · May 5, 2020

Why do you want to use both? Are you tracking potassium and determined an amount that maintains it?

Lousybreed · May 5, 2020

Hello all. So let’s say that KNO3 and NaNO3 are both soluble at 1g/ml to make the numbers easy. I like to mix my chemicals at 80% saturation to avoid precipitation. So my question is are salts solubility additive meaning you could only add 0.4g/ml of each? Or could you add 0.8g/ml of each.
Randy, my next ICP results are due back next week. I have been doing a new method of getting my PO4 levels at NSW with algae scrubbers and cheato by dosing nitrates. Heavy in and heavy out mentality. So I am feeding my growout system very heavily, dosing nitrates, and skimming hard. So when doing this, yes Potassium can become higher than NSW by a wide margin. I know a guy that was over 500ppm of postassium before switching to a mix of NaNO3 and KNO3.

Randy Holmes-Farley · May 5, 2020

Lousybreed said:
Hello all. So let’s say that KNO3 and NaNO3 are both soluble at 1g/ml to make the numbers easy. I like to mix my chemicals at 80% saturation to avoid precipitation. So my question is are salts solubility additive meaning you could only add 0.4g/ml of each? Or could you add 0.8g/ml of each.
Randy, my next ICP results are due back next week. I have been doing a new method of getting my PO4 levels at NSW with algae scrubbers and cheato by dosing nitrates. Heavy in and heavy out mentality. So I am feeding my growout system very heavily, dosing nitrates, and skimming hard. So when doing this, yes Potassium can become higher than NSW by a wide margin. I know a guy that was over 500ppm of postassium before switching to a mix of NaNO3 and KNO3.

One gram per mL? One mL of water weighs one gram. A few things are that soluble, but KNO3 is not one of them.

Let's back off a bit lol

The solubility limit of KNO3 and NaNO3 are tied together by the fact that both dump nitrate ion into solution, reducing the amount of each that can dissolve when the other is already present. This is called the common ion effect.

Instead of my writing out a whole explanation, here's a link to an explanation: