Randy - Potassium Sulfate or Potassium Chloride?

[Thales]

Hey Randy,

In a recent club discussion on K, I thought I read somewhere that you said that potassium sulfate was not a great way to add potassium, and that potassium chloride would be better. After way to long looking for the thread, I could only find posts where you say that food grade potassium chloride would be the way to go, but nothing about potassium sulfate. Am I imagining things? :D

Thanks!

RR

[bertoni]

Potassium chloride would tend to shift the ionic balance less, since chloride is much more common that sulfate in seawater. A mixture of the two might be best, but the sulfate part would be very small. There might be some other issues, too, though.

[Randy Holmes-Farley]

You may be more easily able to find cheap food grade KCl, so that is probably the way to go. :)

[Thales]

Thanks Randy.

People in the club are asking about this:

http://www.aquariumfertilizer.com/Store.php

Potassium Sulfate
Potassium Sulfate 1 lb. K2SO4
Price: $3.00

Do you have any thoughts?

[Randy Holmes-Farley]

A high quality potassium sulfate may be OK, but like magnesium sulfate, will add more sulfate than potassium. Still, that doesn't worry me too much. Similar, perhaps, to a sulfur denitrator adding sulfate.

The other issue is the purity, which I see no mention of for that product. Purity (and ionic balance for that matter) is not as big of a deal for minor supplements where you add nowhere near as much as calcium and alkalinity, but could still be an issue.