K2SO4 vs K2CO3

[jaxal]

K2SO4 (Potassium Sulfate) vs K2CO3 (Potassium Carbonate), Which one is better to use?

PMDD is use K2SO4 but ADA Brighty K is use K2CO3 plus dechorine.

 

[Tom Barr]

Re: K2SO4 vs K2CO3

Well, the K2CO3 adds KH, so unless you also need KH(not likely), K2SO4 is more useful.

But then it's mainly added for extra K+, if you use KNO3, it's extremely rare you need more K+, adding K2SO4 will not hurt though........

Regards,
Tom Barr

 

[FrankG]

Re: K2SO4 vs K2CO3

Tom,

Well, the K2CO3 adds KH

Yes and no. When the plants uptake the K+ ion, they release a H+ ion, which then reacts with the CO3-2 ion to CO2 and water. So once all the K is used by the plants, the KH is where it was before K2CO3 was added.

If you do regular 50% water changes, it probably does not matter anyway.

Regards,
Frank

 

[Tom Barr]

Re: K2SO4 vs K2CO3

Okay, let me ask you this question if you believe that, if you add any carbonate such as Ca++ from CaCO3, will it raise the KH or not?

Try it.
It does not matter if it's K+, Ca++, Mg++, Na+ etc

Plants release H+ all the time for many reasons, not just K+ uptake.
K+ uptake alone is not going to be a major impact on KH nor pH.
Plant use it, but compared to CO2?

KH does not "go away", it can only be split into CO2 and OH by a strong acid (HCL, H2SO4, HNO3 etc), CO2 is a weak acid so all you get is a buffered system. Or by plant uptake under low CO2 conditions........CO2 and KH are buffered system, we can add lots of CO2 and the KH will still be the same. We do that with our tanks. Does your Kh go down when you add CO2?

So we are essentially adding H+'s since the CO2 is a weak acid.
If you add HCL, then the KH will be lowered and split into CO2 and OH.
You can also try these little test(not with your fish!)


Regards,
Tom Barr