Potassium Dosing

labas39

labas39

Active member
I did a bunch of research the last few days and thought I'd share my results along with documenting my findings.

I checked my potassium, K, level using the Salifert Potassium test kit. It's pretty easy to use and very easy to see the color change. From what I've found, it's rather accurate as well. Currently, my K is at 330 which is rather low. I don't run a ULNS so not exactly sure why it's so low but probably due to the salt mix I'm using.

Anyway, I started to dose using Brightwell's Pottasion-P product. Their page is at:

Brightwell Aquatics Potassion-P

There are discrepancies in their directions so I decided to do some research.

The discrepancies are:

  • Under the Basic instructions, they say add 2 grams, or approx 1/2 teaspoon, of Potassion-P but under the Advanced instructions, they say to add 5 grams, or approx 2 teaspoons. The math doesn't add up. So, I found this PDF file that converts weights of compounds to volume:

    Mass-Volume Equivalents of Common Chemical Solids

    In there, they show that 4.5 grams of Potassium Chloride, KCl, equals 1 teaspoon. So, the Brightwell's Basic instructions are more correct: 2 grams is approx 1/2 teaspoon. 2 teaspoons is 9 grams, not 5.

    (Note that the Brightwell page above states that the ingredients of Potassion-P is Potassium chloride (anhydrous), Potassium sulfate (anhydrous). This makes sense since it also states that it's 49% potassium where KCl has 52.5% potassium.)

  • Under the Basic instructions, they say to add 2 grams Potassion-P to 20 gals of tank water but under Advanced, it says to not go over 10 ml of a 5 gram/8 oz. stock solution per 20 gallons of tank water.

    They state that 1 gram brings up 1 gallon of water 129 ppm. In the Basic instructions, 2 grams per 20 gallons will raise the K by:

    2g * 129ppm/20gal or 12.9 ppm

    In the Advanced instructions, the 10ml of stock solution per 20 gallons will only raise the K by:

    5gm/8oz = .625 grams per oz. of stock solution
    10 ml of stock solution = .34 oz.
    Therefore, .625gm * .34 = 2.1 ppm.

    At that rate, I'd have to does for eternity to bring the K level up to 400.

I found a potassium calculator at Ultimate Reefs:

Potassium Supplement Calculator

There, they say not to increase the K per day more than 10ppm. This is more consistent again with Brightwell's Basic instructions.

I want to start by increasing K by 5 ppm per day. Using the Ultimate Reef calculator, I put 100 US gallons for my Volume, 395 for my Current Level and 400 for my Desired Level, which gives me a recommendation of 4 grams. This again matches up with my hand calculations.

So, I'm going to start with 4 grams of K per day. Since I know how much ATO water I use per day, I've been adding it to my ATO water so that it doses throughout the day.
 
Last edited:
jrpark22000 said:
Let us know how it goes. The thought of dosing K scares me and a lot of others.
Click to expand...

I've been scared off myself for a long time. I purchased the test kit and Potassion-P a while ago but when I heard of our local famous reefer's potassium mishap, I held off. After seeing how much it takes to raise the K. I became more bold. Also, Zeovit's do it all the time.

I think the key will be to test, test and test!
 
I've been dosing K for over 1 1/2yrs @ 5 ml once a week and keep it between 380 400 , and test with Red Sea potassium test kit. Take everything slow and you should be good.



Tom
 
I decided to test my old kit with a new one. I bought a new kit last night from [MENTION=764]Reefwise[/MENTION] and I noticed there's an expiration date on the top of the box. My old one expired 7/2014 and the new one expires 5/2016.

That said, the new kit measured 390 ppm.
 
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