Copper Sulfate

Last year, I went to great lengths to mix up a copper sulfate solution, and it pretty much did the trick. But this year, I got a faint whiff of H2S in a couple of batches, and instead of using CuSO4, I took some copper sheets (the kind that they sell in craft shops), cut them up into thin strips, and swooshed them inside my carboy. I "think" I achieved the same results.

Lee

Joe,

I think 10 mg in 1000 ml is a 1% solution. As far as how to measure milligrams of copper sulfate in teaspoons, I have not idea.

Ed

Joe,

Actually, I think it's 10 _grams_ per 1000 ml water to get a 1% soln. At that rate, each ml of soln contains 10 mg of copper sulfate.

HTH, Mike MTM

So I had always assumed that the percentage was in reference to copper itself, rather than copper sulfate. As I remember, copper makes up about 25% (maybe 50%, can't remember) of copper sulfate. CuSO4 5H20 = 64 + 32 + 64 + 90 = 250, so yep, copper = 25% by weight.

It seems to me you'd want to know the percent copper, rather than the percent of extraneous non-reactive materials like water.

Dave

Dave,

I think it has been found to be convenient, perhaps by empirical means rather than by calculation, to use a simple 1% soln of copper sulfate pentahydrate, where 150ml in 1000gal wine yields about 0.1mg/liter. My (unimpeachable) reference for this is Lum's manual, pg 72. ;-) I guess the fact that it's only really 25% Cu has already been taken into account. But Margalit, in "Winery Technology & Operations", pg 151, does speak of adding copper sulfate solution to get 0.05-0.5 ppm copper, without mentioning volume, so I guess that would require further calculation. I like Lum's simpler way.

Regards, Mike MTM

My memory is of having a devil of a time converting between various measures of copper sulfate, including Margalit's. I can't remember why his was such a pain, but somehow it was.

I'm not sure exactly what you have in mind, though. 0.05 - 0.5 ppm implicitly references volume, because it just means 0.05 -0.5 mg/liter.

Dave

See if I have this about right:

From Lum's numbers,

1.5g in 1,000gal

.395g / 1000liters

.395g / 1,000,000g

.395ppm CuSO4*5H2O

Times .25, as you pointed out, for actual wt. Cu

.395ppm x .25 Cu in CuSO4*5H2O = .1ppm Cu dose

It seems to come out as expected, with the % composition of copper factored in.

My stock bottle of 1% copper sulfate bears my note that .75ml soln in 5 gal wine gives 0.1ppm copper. I don't like to trust my calculations any more often than I must.

Tom S

Back when I mixed up my 1% soln (or rather, what I *hope* is 1% soln) I found at least 2 or 3 different articles that you should use 4.01g of copper sulfate per litre of water.

Which, based on the loaded-with-all-kinds-of-disclaimers reply I just posted to your other thread, is just under a teaspoon per litre ;-)

Cheers, Richard

Tom and MikeMTM

You guys are right - I should have said gram and not milligram - I need to read my spreadsheet column labels better the next time I respond. Thanks for giving the correct information.

Ed