# K2SO4 (potassium) question



## Kubla (Jan 5, 2014)

What else are you dosing, how much, how often?

If you haven't already you should look into different dosage methods. The main ones are PPS and EI. EI seems to be the more popular here. Basically daily dosing of ferts providing the plants with a little more than they can use and then resetting the levels once a week with a 50% water change. Take a look at the stickies in the fertilizer section.http://www.plantedtank.net/forums/11-fertilizers-water-parameters/184531-fertilizer-water-parameters-faq.html Lots of good info there to get you going.


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## Django (Jun 13, 2012)

1. Using EI, you can just dump the whole dose in. The fish don't like it when you do, but they tolerate ok.

2. With Estimative Index (EI), you flush out the tank by changing some of the water, removing some of the remaining ferts and add another dose of ferts. Once a week, and EI requires 50% water change.

3. See 2. There are recipes for EI ferts here on the forums http://www.plantedtank.net/forums/11-fertilizers-water-parameters/647697-dry-dosing-nutrient-solution-recipes.html and I use 1/4 Nico something sells dry ferts for mixing up.

Oops - I did a member search for nico and didn't find him. I hope the post is still there.


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## Kubla (Jan 5, 2014)

The member name is Nilocg.


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## PortalMasteryRy (Oct 16, 2012)

K is not typically a problematic nutrient. I have had 20,30,40,60,80 and 100+ K ppm levels in my tanks with no issues. The highest I did was 150 ppm K and this was tested by a laboratory. On Average, I keep my K levels around 40-60 ppm (high tech tank) and not worry about it too much. Usually if the Ca/Mg levels are higher then I try to keep my K higher too. Like what Django suggested, you can dose for the target K after a water change and forgot about it.

Typically the K levels will get higher if you are dosing KNO3 and KH2PO4. 

There are also freshwater K tests that are available. Unfortunately they are very expensive and not worth the money unless you own multiple tanks.

Potassium Portable Photometer - HI96750 - Hanna Instruments

Benchtop Multiparameter Photometer for Water Analysis - HI83200 - Hanna Instruments


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## Chip Munk (Nov 12, 2016)

Hello Kubla,
I'm revisiting that after reading a Tom Barr post.

Bump: Thank you PortalMasteryRy,
I hear ya. And that $900 meter would make a great stocking stuffer. 

Looks like I have some lighting to buy.

~Chip


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## Pulsar (May 13, 2016)

hi. I have question about K.. i tried EI 3 times and always had problem with melted top of the plants.. with GH around 5. it always was too high potassium around 20ppm. i Used K only from kno3. circulation was good, Degassed tank was 7.8ph with co2 on was 6.2ph lights was ok. ferts: NO3 30ppm, K 20PPM, po4 3PPM. micro 0.5ppm Fe. where is the problem? still to low CO2?


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## Surf (Jun 13, 2017)

Generally plants need more nitrogen than potassium. So if you are dosing to 10ppm NO3 with potassium nitrate and 1ppm PO4 with potassium phosphate you should have more K tan you need. The primary reason to add potassium sulfate is not to increase potassium, but to increase sulfur. Sulfur is a macro nutrient that plants need. 



> Note: I am using RO water that I buffer and control GH. I mention that because water changes alone will not add any K2SO4 to my aquarium.


If you are using a sulfate GH booster you already have enough sulfur in your tank. Adding potassium sulfate in your case is not necessary. Sulfate GH booster such as Seachem Equilibrium use the ingredients calcium sulfate (Gypsum) and Magnesium sulfate (Epsom salt). Other GH formulas on the market are chloride based made by mixing calcium chloride and magnesium chloride.plants don't need a lot of chlorine (it is a micro nutrient). Many people just buy the ingredients and make there own GH booster. 

Additionally many GH boosters on the market include potassium even through it is not detected by the GH test.


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## Edward (Apr 11, 2005)

Pulsar said:


> … it always was too high potassium around 20ppm… ferts: NO3 30ppm, K 20PPM, po4 3PPM. micro 0.5ppm Fe. where is the problem?


 Water column 20 ppm of K is not high, it is rather medium low. The NO3 30 ppm, PO4 3 ppm, K 20 ppm and Fe 0.5 ppm are water column concentrations?


PortalMasteryRy said:


> K is not typically a problematic nutrient. I have had 20,30,40,60,80 and 100+ K ppm levels in my tanks with no issues. The highest I did was 150 ppm K and this was tested by a laboratory. On Average, I keep my K levels around 40-60 ppm (high tech tank) and not worry about it too much. Usually if the Ca/Mg levels are higher then I try to keep my K higher too. Like what Django suggested, you can dose for the target K after a water change and forgot about it.


 Thanks for sharing, it is very helpful in the era of potassium hysteria.


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## cl3537 (Jan 28, 2019)

Pulsar said:


> hi. I have question about K.. i tried EI 3 times and always had problem with melted top of the plants.. with GH around 5. it always was too high potassium around 20ppm. i Used K only from kno3. circulation was good, Degassed tank was 7.8ph with co2 on was 6.2ph lights was ok. ferts: NO3 30ppm, K 20PPM, po4 3PPM. micro 0.5ppm Fe. where is the problem? still to low CO2?


Sounds very close to my tap and tank parameters kh=5, gh=8 tap ph=8.0 and I drop it to 6.5. I had trouble with EI ferts as well but its very plant species specific and how heavy you plant. I don't think its specifically the K, but it could be too much Fe or many other things. I find I get Algae if I increase N even past 10ppm but that is with my low plant mass (see my signature).

Don't listen to the nonsense about not enough CO2 if you have a 1.6ph drop and reasonable amount of light its unlikely to be that unless you have flow issues.

It depends on the plants but if you have Lythraecae like Rotalas or Pogostemon Erectus or similar family they likely won't like that heavy ferts in hard water.


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## Pulsar (May 13, 2016)

Level of K depends from Gh. I know that you can have in hard water potassium on 80ppm but in soft water is a little bit diferent Tom Barr has in soft water GH3 concetration of K 40ppm with no issue. i think i did something wrong and potassium around 25ppm concentration in the tank did disaster.. i'ts not high Fe or micro. with Fe 0.3 i had the same efect. so i'm looking the source of the problem. not enough Co2? or light.. i have Led 26W but i think maybe change on 4x 24W T5 on 63liters.
Concetration in tank i have right now Gh6, Kh3, Ca30ppm, Mg 7ppm, K 7ppm, NO3 30ppm, Po4 2,5ppm
i'm useing iron gluconate so i can't measure Fe. i thing is around 0.3ppm. Ph was 6.3 now i have 5,8.
My Plants :
Tonia Belem, Giant, Madeira, Fluviatilis , Erios several types, Pantanal. mostly the harder stem plants.


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