Hi all,
Just use only RO water or very soft water for a while, it's safer for plants.
I wouldn't advise copper either, but I can do the calculation. "Copper sulphate pentahydrate" is CuSO4.5H20, this is the hydrated form, which is stable. Anhydrous CuSO4 is colourless, but even if you bought it as CuSO4, unless you stored it in a desiccator it would become the familiar blue pentahydrate.
You need to know the RMM of the pentahydrate, which is 249.7 g this is from Cu + S + (O*4) + H (5*2) +(O*5), which is 63.5 + 32 + (4*16) + (10*1) + (5*16) = 63.5 + 32 + 64 + 10 + 80 = 249.5 (and some rounding errors).
The percentage copper is 64.5/249.7 = 0.255 = 25.5% Cu. So 1g CuSO4.5H2O contains 0.255g Cu.
We know need to do some mucking about with dilutions to get to ppm. If we use the powers of 10 this becomes easier, 10^6 is a million (1 followed by 6 noughts) and 10^-6 a millionth 0.000001, this has the prefix "micro".
10^3 is a thousand (1 followed by 3 noughts), and 10^-3 a thousandth 0.001, signified by the prefix "milli".
1 milligram in 1 litre = 1ppm (a million is 10^6 and 1ppm = 1 millionth (10^-6), we have 10^-3 to go from litre to a gram (which weighs 1000g), and then from a gram to a milligram is 10^-3 grams)and we have 0.255g which is equal to 255 milligrams, therefore:
1g of CuSO4.5H20 mad up to 1000g with water (H2O) = 255 ppm Cu, but 1g in 100litres = 2.55ppm Cu might be more useful.
cheers Darrel
