@Nutty sKunK
You have to be very careful with copper ions. The toxic range is just above the effective nutrient concentration. You can kill a plant fast with a very small amount. Copper in hydro is usually held to 0.04 to 0.2 ppm.
if you want to add copper, I’d make a 0.05 ppm solution of copper sulfate pentahydrate (blue crystals, available as drain root killer) then drench the soil with it.
To make that solution, I would use a serial dilution strategy as follows. 0.05 ppm copper is 0.2 ppm copper sulfate pentahydrate.
1) Make a 20.0% solution by dissolving 20.0 grams copper sulfate in pure water to make 100.0 ml solution.
2) Measure out 10.0 ml of that blue solution and add pure water to 1000. ml; this is now a 0.20% solution which is 2000 ppm copper sulfate.
3) Take 10.0 ml of the2000 ppm solution and dilute to 1000 ml. This is a 20 ppm solution.
4) Take 100 ml of the 20 ppm solution and mix it with 9.9 liters water to make a 0.2 ppm copper sulfate (0.05 ppm copper) solution. Drench the soil.
That said, I doubt copper is your issue. I recommend fixing that rather than risk a copper overdose. While your soil doesn’t list a copper content, all soil contains some.
