What is the difference between potassium sulfate vs potassium nitrate?

Eliden · Oct 29, 2017

What is the difference between potassium sulfate vs potassium nitrate?
Which is better?

smokin'reefer · Oct 29, 2017

Bump for I good question. I was wondering this myself recently.

Flippers4pups · Oct 29, 2017

@Randy Holmes-Farley.

@jsker, @d2mini can we get this moved over to the reef chemistry forum?

Flippers4pups · Oct 29, 2017

I'll try to answer this one. Dosing potassium, is what I'm assuming question is about. Potassium nitrate would be safer long term to dose, as opposed to potassium sulfate.

The reason is the increase in salinity over time. The build up of salt in the potassium sulfate dosing. Build up if sulfate in the system as well.

Randy would be the one to go into details better than me.

SashimiTurtle · Oct 29, 2017

KNO3 will increase potassium and nitrates. I've used it for nitrate dosing when I was fishless. K2SO4 contains sulfur and I'm not sure you'd want to be dumping that into your tank.

Randy Holmes-Farley · Oct 29, 2017

Eliden said:
What is the difference between potassium sulfate vs potassium nitrate?
Which is better?

Depends on what it is for.

If the purpose is to boost potassium, I'd use potassium chloride as first choice, potassium sulfate as second choice, and not potassium nitrate except under very unusual circumstances (you need nitrate and hardly any potassium).

If the purpose is to boost nitrate, potassium nitrate is a second best choice to sodium nitrate since it also boosts potassium which you may not want. Potassium sulfate, clearly, has no effect on nitrate.

Randy Holmes-Farley · Oct 29, 2017

Robin Haselden said:
KNO3 will increase potassium and nitrates. I've used it for nitrate dosing when I was fishless. K2SO4 contains sulfur and I'm not sure you'd want to be dumping that into your tank.

Sulfate is the second most abundant anion in seawater, after chloride. It is present at something close to 2,700 ppm, so a few more ppm is not any concern, but long term, chloride would be the better bet if you need to dose a lot of potassium.