Tested potassium today to find it down at 320

Discussion in 'Reef Chemistry by Randy Holmes-Farley' started by rock_lobster, Jan 1, 2018.

  1. rock_lobster

    rock_lobster Valuable Member R2R Supporter

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    I dont do water changes so it is inevitable that I will have to dose potassium. I also use the red sea ABCD according to Alkalinity consumption it has potassium but apparently it is no where near enough. I am just a little curious about this math. I purchased potassion P and the product states 5grams/8oz stock solution and to dose it at a Maximum rate of 10ml/20gallons/day.

    However it also states that the solution will raise the potassium at a rate of 1.7ppm per 1 ml stock solution per gallon. So from that it appears that they are suggesting that the maximum rate of raising potassium with their product is .85ppm per day? which is probably less than my consumption rate. So should I try and calculate my daily consumption rate and then add that to the max dosing rate?
     
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  2. Randy Holmes-Farley

    Randy Holmes-Farley Reef Chemist Staff Member Team R2R R2R Supporter R2R Excellence Award Article Contributor Expert Contributor

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    I would not say it is inevitable. To be honest, I'm not sure why there aren't just as many tanks rising in potassium as dropping, since there's no reason that foods do not have as much potassium in them (relative to N and P) as do tissues formed in the tank. Maybe it is lost in processing...

    When companies give max rates, it often assumes you are not measuring things.

    I'd boost it a lot more than that. :)
     
  3. JimWelsh

    JimWelsh Well-Known Member R2R Supporter

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    Their web page for this product says more or less everything the OP said above, but it also specifies that the product is 49% potassium. Based on that, their number of 1.7 PPM is, by my calculations, incorrect. It should be 2.7 PPM. Here's the math: 49% of 5 grams in 8 oz of water is 2.45 grams of potassium in 236.6 mL of water, or 10.36 mg of potassium per mL. That 10.36 mg of potassium divided by 3.785 liters of water = 2.74 mg/L.
     
  4. TheEngineer

    TheEngineer Formerly icecool2 R2R Supporter Reef Squad R2R Excellence Award Showcase Editor Build Thread Contributor Delaware Reef Club

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  5. JimWelsh

    JimWelsh Well-Known Member R2R Supporter

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    Straight potassium chloride is 52.4% potassium. Straight potassium sulfate is 44.9% potassium. Most reef products (such as Brightwell's) would likely be a mixture of these two in a ratio designed to maintain NSW SO4:Cl ratios. While I'd hardly call 52.4% "much more potent" than Brightwell's 49%, it is very likely much less expensive to use straight potassium chloride, as long as the SO4:Cl ratio doesn't get too out-of-whack.
     
  6. Randy Holmes-Farley

    Randy Holmes-Farley Reef Chemist Staff Member Team R2R R2R Supporter R2R Excellence Award Article Contributor Expert Contributor

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    It is remarkable that Brightwell makes so many similar mistakes.
     
  7. TheEngineer

    TheEngineer Formerly icecool2 R2R Supporter Reef Squad R2R Excellence Award Showcase Editor Build Thread Contributor Delaware Reef Club

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    Potent was the wrong word :) It takes less of the food grade stuff to have the same effect. The potassium chloride is 365 mg of potassium per 1/8 tsp.

    Using the numbers from Brightwell, 1/4tsp raises a gallon of water by 129ppm. 1/4 tsp of the food grade stuff raises it 193ppm. That’s almost 50% more bang for the volume added. I’d venture to say the food grade is probably significantly cheaper. I got 8 oz for $4 shipped.
     
  8. JimWelsh

    JimWelsh Well-Known Member R2R Supporter

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    Ahhh. I see. "Dense" was the word you were looking for.
     
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  9. TheEngineer

    TheEngineer Formerly icecool2 R2R Supporter Reef Squad R2R Excellence Award Showcase Editor Build Thread Contributor Delaware Reef Club

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    You making fun of me!? Lol (joking)

    Dense is a better word :)
     
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  10. Steved350

    Steved350 Active Member

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    Lol. Good info
     
  11. rock_lobster

    rock_lobster Valuable Member R2R Supporter

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    Makes a lot of sense. I've actually tested low potassium a few times over the years and when I dosed the correct amount over a few week period I always noticed that my final potassium was much higher than the product stated it should be according to the dosing. 2.7ppm/ml is pretty much exactly the gain that I got from dosing to replenish.
     
  12. rock_lobster

    rock_lobster Valuable Member R2R Supporter

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    I bought the 300g potassion still pretty cheap at 10$ and it should last me at least a decade haha. Probably longer now that I find out that their dosing is wrong.
     
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  13. rock_lobster

    rock_lobster Valuable Member R2R Supporter

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    I feed quite heavily and I do consistently lose potassium. I calculated the rate to be .33 ppm per day over the last 4 years and that is also including the dosing of red sea ABCD and some very small water changes maybe 20% per year total.
     
  14. Randy Holmes-Farley

    Randy Holmes-Farley Reef Chemist Staff Member Team R2R R2R Supporter R2R Excellence Award Article Contributor Expert Contributor

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    Ever check your new salt water at the salinity you use? 0.33 ppm per day is not likely to be from your small water changes, however.
     
  15. rock_lobster

    rock_lobster Valuable Member R2R Supporter

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    I havent tested the salt I use but It is really a minimal amount. My tank is only 20g but loaded with SPS. I dont actually even make water for changes. I just test salinity once a month and if it is a little low from sharing frags then I will add a tablespoon of dry salt right into the rear compartment. I do that no more than once a month sometimes Ill go several months with added adding any salt. I use reefcrystals.
     
  16. rock_lobster

    rock_lobster Valuable Member R2R Supporter

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    I dose a lot of soda ash, calcium and magnesium so that probably keeps the salinity up for the most part to counter the fragging.
     
  17. rkpetersen

    rkpetersen Lesser-Known Randy R2R Supporter R2R Excellence Award Partner Member 2018

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    The extensive mind-numbing run-on verbiage on the sides of their bottles indeed actually says very little and is often inaccurate. Also, their dosing recommendations can easily lead to overdosage, in my opinion and experience.

    BTW, I still have unexplained elevated potassium in my tank, well over 500. I still think the source is Reef Fusion 2, after testing everything else, but I haven't bothered to switch to a different 2 part yet. Maybe OP and I should exchange some water. ;Shifty
     
  18. rock_lobster

    rock_lobster Valuable Member R2R Supporter

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    HAHA that would be perfect! well it must be the food that you are using in your case if the salt checks out.
     
  19. rock_lobster

    rock_lobster Valuable Member R2R Supporter

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    I am just going to start adding the KCl directly to my dosing regimen 3ml week should be perfect. Funny how I bought spectracide to dose nitrates but then moved to NaNO3 to avoid messing with potassium. Now it actually looks like it might be perfect for my tank.
     
  20. Randy Holmes-Farley

    Randy Holmes-Farley Reef Chemist Staff Member Team R2R R2R Supporter R2R Excellence Award Article Contributor Expert Contributor

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    Now that you remind me, that process alone reduces potassium, since those additions boost salinity, and correcting it back to normal over time reduces everything else, including potassium.

    Adding 1.1 dkh per day will raise salinity about 32% per year and hence will reduce potassium by about 0.088% per day, or 0.35 ppm per day. :D
     
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