Potassium

[Boohoo]

From reading some of the posts in regards to potassium and plants, is there a test kit for measuring potassium? I have seen phosphate tests at my LFS but none for potassium. And what do you buy if you need to add it? Is there something just called potassium out there?

[reiverix]

I'm not aware of any way to measure potassium levels unless you have access to some kind of laboratory. You can buy some K2SO4 from gregwatson.com (http://www.gregwatson.com/) or you could get a hold of some Nu Salt (salt substitute, more expensive) from a grocery store.

For dosing, I add around 25ppm after my weekly 50% water change.

[Boohoo]

This is probably stupid but if there is know way to measure how do you know your dosing to 25ppm? What amount do you add and how big is your tank?

[tyella]

BooHoo,
Try this link:

Chuck Gadds Dosing Calculator (http://www.csd.net/~cgadd/aqua/art_plant_dosage_calc.htm)

You can either call your local water utility and ask if there is potassium in the water and calculate from there, or assume there is none in the water and dose the water you add during water changes. So at each water change you are adding water that has XX ppm (AKA mg/L). Substitute your desired final concentration for XX.

Tony T.

[beviking]

The water co. may tell you they don't test for it. Why? B/c it generally isn't a health concern. Same goes with your flora/fauna. It won't hurt them even at level exceeding...oh, forgot the level...I think Tom Barr quoted it once...anyway, it's considered safe to dose 40ppm/week if you're doing 50% water changes. 80ppm sticks in my mind as being the at/even above level but don't quote me on it.
Most hardware shops sell 40lb bags of KCl for water softeners for ~$7 US. Pretty cheap but the "briquettes" don't dissolve nearly as nicely as the NuSalt does.

[Timmain42]

Gah!

Water softeners BAD! I picked up a 40 lb bag of "water softener" 18 months ago when I went back to IL for Xmas. I started using it to dose for potassium... and wondered what the hell was going on when my plants started showing nutrient deficiencies! Turns out, the "softener" rips Magnesium and Calcium out of the water to make it soft! Not good.

IMHO, stick with NuSalt or GregWatson.Com. Like all advice, you are under no obligation to listen to me whatsoever, just thought I'd throw that out there for ya.

[beviking]

Gah!

Water softeners BAD! I picked up a 40 lb bag of "water softener" 18 months ago when I went back to IL for Xmas. I started using it to dose for potassium... and wondered what the hell was going on when my plants started showing nutrient deficiencies! Turns out, the "softener" rips Magnesium and Calcium out of the water to make it soft! Not good.


:confused: Timmain42, you're not retorting my claim to use KCl USED in water sotfteners (NOT to be confused with actually using a water softener) are you? Definitely no water softener, but using the KCl (which NON-fish keepers use for THEIR water softeners) is o.k..

[Timmain42]

No, I'm saying be careful of what you buy. Not everything is actually good for your tanks... the bag I picked up was marked "potassium chloride/water softener," and it did way more harm than good.

Since then, I have just preferred to stick to what I know works. Like NuSalt and Greg's place.

[reiverix]

This is probably stupid but if there is know way to measure how do you know your dosing to 25ppm? What amount do you add and how big is your tank?
I use a calculator to measure how much I add in. Around 2.5 tsp will raise add 25ppm in my 75g.

[Quartermain]

That calculator you suggested says I should use 40 Tablespoons (2.5 cups!) of KCL to raise the K level in my 20gal tank to 25ppm (assuming it's at zero now). That can't possibly be correct, can it!?

-edit-

ahh.. never mind. I see now how the calculator works. I create a solution and each ml of that solution increases ppm by so much. got it.

-edit-

I don't know if this will help anyone but it is easier to store this stuff in solid form. 1/2 tsp of KCL will raise 20gal of water to almost exactly 20ppm K. It's easier to measure this way too. Dissolve a level 1/2 teaspoon in a small container of aquarium water and just dump it back in. Bingo... 20ppm. Probably best after a weekly water change.

[tyella]

That was close!!

You almost had to start a NEW thread!

[Quartermain]

we wouldn't want that. :D

[Boohoo]

Okay, so I bought this No Salt stuff at the grocery store today. Now most of you folks live south of me, so is this stuff that I'm looking for? Ingredients are potassium chloride, potassium bitartrate, adipic acid, fumaric acid, silcon dioxide, mineral oil. BTW I tasted it and I wouldn't trade my salt for that crap. Can"t imagine No Salt on french fries!!! :thm:

[Paccula]

Okay, so I bought this No Salt stuff at the grocery store today. Now most of you folks live south of me, so is this stuff that I'm looking for? Ingredients are potassium chloride, potassium bitartrate, adipic acid, fumaric acid, silcon dioxide, mineral oil. BTW I tasted it and I wouldn't trade my salt for that crap. Can"t imagine No Salt on french fries!!! :thm:

That's the stuff. I asked this same question when I first bought it :p:

[Boohoo]

okay, Thanks. :)

[happychem]

That's the exact same stuff as I have. It's mostly KCl, the rest of those are basically anti-caking agents. Yeah, it does taste pretty terrible, that's why very few people use salt substitutes.