silly potassium question

[crazycat]

so i dry dose K. i take a cupful of tank water, add my dry k2s04 and stir. then i pour it into the aquarium. i try to evenly distribute it as i pour. as we all know, k2s04 doesn't dissolve real well in water. so my question is, do the plants that get the k poured directly on them get fetilized better than other plants not directly under the stream from my cup? do the particles stay where they fall, or does enough of it enter the water column?

i've been having a lot of potassium issues in my tank...i've resorted to majorly overdosing to try to satisfy my swords (i also added root tabs for them). but i'm still a little confused and frustrated.

 

[QTOFFER]

Moved to planted tank forum.

I'm still a noob to fertilizing aquatic plants, but I know that terrestrial plants are subject to burning when dry ferts are dropped directly on top of them. I would try to dissolve all the K2SO4 you are adding - even if it takes a couple cups of tank water.

Eventually, the particles would dissolve and enter the water column. Rooted plants like swords may take up K in the form of root tabs faster, unlike plants that absorb nutrients directly from the water (Java fern, moss, etc).

Check out Malkore's sticky about ferts. There's a link to Chuck's Aquarium Page where you can find a great calculator for dosing potassium, among other things.

Right now, I'm using Flourish-Potassium liquid, until I can find a cheap source of K2SO4. It's easy, but expensive.

 

[workfortheman]

I pour about 5 cups of hot/lukewarm water in a bowl, and mix my ferts in that. The increased temperature really dissolves them fast, then quick dumpsies into the tank! The small amount of hot water won't affect temp of the tank at all!

 

[crazycat]

aha! perhaps THAT"S why my plants have been suffering! maybe they are getting burned! i will do some research on k burninbg leaves.

workfortheman--i will try your method next time! thanks!

 

[malkore]

See, I have no problems getting 1tsp of K2SO4 to dissolve in 8oz of tank water. I have a little 12oz rubbermaid thing with a lid, so I just shake it.

I mean, yeah there's a tiny bit that goes undissolved, but when I pour it into the tank, it's gone before it hits the bottom.

Now, if you wanna talk about potassium fert that won't dissolve, try some KCl. I hear you have to heat the water to 180degrees F to get it to really dissolve well.

 

[crazycat]

aha--but i use WAY more than 1tsp. but i think workfortheman's solution might help.

hey malkore, do you know whether undisolved potassium will burn a plant's leaves? that could explain a lot of the leaf damage i'm seeing if it's true...

 

[Simpte]

KNO3 dissolves better than K2so4. Warm watter will help but hot water is not adviseable.

 

[crazycat]

thanks simpte, but i don't currently dose no3--my bioload keeps the no3 at 20ppm. but i definitely do need to dose k. that's why i have to deal with k2so4 :?

 

[crazycat]

perhaps it's the salt in potassium sulfate that burns the leaves... ??