I've been EI dosing and doing fine with it. I've been using KNO3, but want to switch over to more K2SO4, since I think my nitrates are fairly high, judging by my cheapo testing kit, my fish load and my probable overfeeding.

My friend had a 50# bag of "potash of sulfur" which I read was the same as K2SO4 -- he uses it to fertilize regular garden plants. This stuff is 50% potassium, 17% sulfur. I don't always trust what I read on the internet, so does the picture below look like K2SO4 to you all? Thanks in advance.

I use the stuff from aquariumfertlizer.com, which works well. I actually tried to find that stuff at garden supply places, but I never could. It looks like typical garden ferts. The real question is what is that other 33%? I would say try it for a day or two and see what happens. Do you know how pure it is?

Yeah, I'd better not chance it. I'll just order some from aquariumfertilizer.com to be safe. Thanks for the tip.

I tried to use "Potash of Muriate" which is supposed to be KCl, but I don't know what the hell it was. It was this crazy red color...I didn't know what I was doing. I tried it and nothing died, but I wasn't even sure what I was adding to my water.

That does look like it.

Regards,
Tom Barr

Will the purity be about the same as with stuff from aquariumfertlizer.com ?

Creighton,

Mine is probably pure because the bag says "All nutrients derived from sulfate of potash" -- probably the same 50# bags as K2SO4 vendors buy. I still ordered some from aquariumfertilizer.com, just to be on the safe side. I have too much money invested in fish to take any chances -- besides the money, I like my fish.

K2 = 38 = 2 X atomic number for K
S = 16
O4 = 32
Total = 86
Therefore: K = 38/86 = 44% (assuming no water is in the crystal form)
S = 16/86 = 17%
O = 32/86 = 37%
But, there is some water in that crystal form, so the percentages are somewhat different.

I feel so dumb right now... . Hoppy thanks for the calculations.

I wish I could get ahold of that stuff. I looked so hard for about a month and then just broke down and bought some offline.

I think we actually just found a reasonable supplier for the stuff. A structural engineer friend of mine in Huntsville, AL has found a chemical supplier that sells 50 pound bags for around $15. I think they have KNO3 as well, but to buy the KNO3 you have to register with the departmet of homeland security as you can make explosives with the stuff. Big brother is watching...