DIY Potassium

[Nick Rose]

I got a ICP test back and it shows that the Potassium is at 311ppm. I would like to raise it to 400ppm. Would I be able to use this Potassium Chloride from amazon its $17 for 2.2lbs where as brighwell is $20 for 1.3lbs. My corals have not been looking happy and I'm wondering if its because of the low Potassium?

 

[Drysea]

You can probably us that but sometimes purity or rather impurities can be an issue with some chemicals that you get from “non reef” sources. K might be your issue but that would not be my first place to look. Macros like alk ca mg would be my first look along with proper light spectrum and intensity and proper water flow. I know it might sound crazy but if you have a completely cycled tank and limit the feeding sometimes the corals can be starving for some N. You can feed a bit more or is your phosphate is as high as you dare and your N is at or very near zero you could carefully dose K over time in the form of potassium nitrate. Dosing all your cations with chloride anion can build up chloride over time.

 

[Nick Rose]

Well my parameters are: 1.026, Ca430, Mag1400, dkh7.5, No310, Po4 .3, Ph8, Temp78. Lights 2 AI VEGAS blues 60, white 18, green 10, red 5(PAR is from 65-180). Flow 1k Gyre at 50%.

 

[Drysea]

What kind of corals are you growing? What are they doing?

 

[Nick Rose]

Frogspawn, Duncan, Candy Cane, Chalice, zoas, mushrooms. Chalice was doing great but has receded and now only has a few mouths left. Candy canes have receded. Frogspawn are not as puffy as they use to be and tissue is receding. Zoas and mushrooms are doing good. The day before the water change the Frogspawns aren’t as puffy but then after I do a water change they become puffy again. I did the ICP test before the water change and then a day after the water change. Only thing that changes is the strontium and Potassium. Before the water change they are low and then after they increase.

 

[Randy Holmes-Farley]

That looks like an excellent product,. I'd use it before I trusted any Brightwell product that did not list a quality grade. Food grade is a very good assurance of purity.

So sad, however, that the world has come to the point where it lists gluten free and non GMO on an inorganic salt.

 

[Drysea]

Well it won’t hurt to bring it up some I’ve generally noticed more color issues with potassium than tissue retraction. Interesting that those are the only things that change with the water change

 

[Nick Rose]

Interesting that those are the only things that change with the water change

I try and keep main elements (Ca,Mg,dkh)close between the new water and the tank. One thing that is strange is that I did a test in September and two elements have gone up from then. So Silver went from .0008 to .0234, Uranium went from .043 to .102. Also my Silcon is at .259

 

[Drysea]

Those others must be source water contaminants. Do you use DI water?

 

[Nick Rose]

Yes. Sediment, 2 carbons(I’m replacing next week because I’m testing positive for Chlorine on the waste water), ro membrane, di. The TDS of the tap is 24 or lower and out of the membrane is no higher then 1 and product water is 0

 

[Drysea]

Who knows... some numbers to back up water changes I guess

 

[Nick Rose]

That looks like an excellent product,. I'd use it before I trusted any Brightwell product that did not list a quality grade. Food grade is a very good assurance of purity.

So sad, however, that the world has come to the point where it lists gluten free and non GMO on an inorganic salt.

How would I make a 1 gallon solution for dosing. Would this be correct?

Potassium chloride has a solubility of 34.2 g / 100 mL of water @ 20 C, so our solution must be less concentrated than that. Let's choose an arbitrary concentration of approximately half that by dissolving 150 grams of KCl in enough water to make up a total volume of 1000 mL. Since the Molecular Mass of KCl is 74.55, that gives a molarity of 150 / 74.55 = 2.012M in our solution. Since the Atomic Weight of potassium is 39.0983, then each mL of our solution will contain 2.012 * 39.0983 = 78.67 mg of potassium. In order to raise the potassium level of 100 gallons of water by 10 PPM, we need to add 10 * 100 * 3.7854 = 3785.4 mg of potassium. So, it will take 3785.4 / 78.67 = 48.12 mL of our 150g / 1000 mL KCl solution to accomplish this. For your 127 gallons, you would need 48.12 * 127 / 100 = 61.11 mL of our solution. This is assuming your KCL is 100% pure; your MSDS indicates a slightly lower concentration of KCl in the substance you are using. Adjust the numbers above accordingly, if you wish.

I also saw this link for a potassium calculator. Is one better over the other for dosing?

 

[Randy Holmes-Farley]

Who knows... some numbers to back up water changes I guess

Good chance the silver and uranium are just test error. I’d ignore them.

 

[Nick Rose]

Good chance the silver and uranium are just test error. I’d ignore them.

I'm using the ICP-Analysis which I know you and other fellow reefers don't trust. One thing I learned from this last test was that they are discontinuing the Bromine test because the Argon gas they use comes with some bromine in it. So with the two samples I sent in one had a result of 34ppm while the other was 227ppm.

 

[Nick Rose]

Are you sure you're consuming enough potassium to require it to be on a doser? Potassium can be consumed in reef tanks, but needing to add it so frequently that it has to be on a doser sounds like testing error.

Regardless, you can use potassium chloride powder to make your own stock solution. I would choose a powder that is at least food-grade, like this one from Etsy.

You could make a stock solution of any strength. I personally would shoot for something generic, like 1 ml per 10 gallons gives a 1 ppm increase in K. To do this, mix about 72.187g of KCl in 1 liter of water. KCl is about 52.44% K by weight. So, 72.187 g in 1 liter of water will give you about 37.854 g/L of K, which is about 37,854 ppm. 1 mL of this solution should raise 10g of tank water by 1 ppm. To make one gallon of this solution, add 280g of the KCl to one gallon of water.

It looks like from your other posts that your tank is 165 gallons. To calculate doses of this supplement, multiply the ppm increase you want by 16.5. Let's say you want a 10 ppm increase of K. You would need to dose 165 ml (16.5 * 10 = 165 mL).

Randy or anyone else, feel free to double check my math

@Randy Holmes-Farley Is this the correct math to make a 1 gallon solution for dosing?

 

[Nick Rose]

@Randy Holmes-Farley I just got the potassium chloride that I linked in the thread but it has a slight smell of brown sugar. Is that normal?

 

[Nick Rose]

@Randy Holmes-Farley Will Potassium Chloride raise Alkalinity. I've been dosing 30ml of the one gallon solution since the 16th of December. The dkh was 7.7 but now its 10.65. I dose 15ml of 2part. Alkalinity is the only parameter that has changed. Also is the Salifert test kit accurate? I just bought one and its giving me a reading of 330.

 

[Nick Rose]

Just answered my own question. I tested my newly mixed 10 gallons of saltwater and it was reading 310ppm of K and 9.3 dkh. So I added 90ml of the 1gallon and it brought the K to 380 and dkh to 9.75.

 

[Randy Holmes-Farley]

FWIW, Pure potassium chloride doesn’t smell or impact alkalinity.

 

[Nick Rose]

@Randy Holmes-Farley That’s what I thought. I’ll have to buy a different one then.

I guess I should have gone with the one you suggested in past threads.



I wonder if this lab grade one would be even better? Would I have to mix this differently?