Can someone check my math?

[Doob]

Hey oh! I’m looking to do a correction dose for potassium. I’d like someone to double check my math. I had found a post of Randy walking someone through this, but now I can’t find it.

Recent ICP/MS showed potassium at 351ppm. I have a bottle of potassium chloride from loudwolf. 113g total. Take is about 130gallon net total volume.

So if I put it all in a solution, I’d have 113mg/ml of potassium chloride.

Since it’s 52% potassium by weight, that would make the solution 58.76 mg/ml potassium.

So I ml would raise potassium level in the tank by .119mg/l or ppm. All of the solution would raise the concentration in the tank by 119ppm.

 

[Doob]

Actually, so as not to have leftover solution that I need to store, what I’ll do is dissolve 47.5g into 250ml of RODI.

That makes a solution of 190mg/ml potassium chloride, 99mg/ml potassium.

Each ml will raise concentration by .2ppm, and all 250 ml will raise it my desired 50ppm.

I would do this over 2-3 days.

 

[Randy Holmes-Farley Verified Community Expert]

Tank size is needed.

It also may not be exactly right for the stock since the 250 mL may rise as you dissolve that much KCl in it. Better is to think of it as mg K per g total.

Then you weigh out the dose.

 

[Doob]

Oops, typo up top. “Take is about 130gallon net total volume.” should say tank.

I see the dilemma about ending up with more than 250ml after dissolving it. If I mix up the solution as described though, and dose all of it, I get to where I want to be though, right?

 

[KStatefan]

Actually, so as not to have leftover solution that I need to store, what I’ll do is dissolve 47.5g into 250ml of RODI.

That makes a solution of 190mg/ml potassium chloride, 99mg/ml potassium.

Each ml will raise concentration by .2ppm, and all 250 ml will raise it my desired 50ppm.

I would do this over 2-3 days.

Pretty close to the same as what I get.

 

[Doob]

Pretty close to the same as what I get.

w00t! Thanks. Nice spreadsheet