First off, many thanks to
@Christoph for providing me with this information in the first place. The below "recipe" can also be found in a book by Gerald Bassleer:
https://www.bassleer.com/over-gerald-bassleer/
Into 1 liter of RODI water add:
4 grams Copper(II) sulfate pentahydrate (CuSO4.5H2O)
AND
0.25 gram Citric acid - the acid acts as a stabilizer to the copper in solution.
Never substitute the citric acid with ascorbic acid (Vitamin C) since it will render the copper way more toxic.
Everything should dissolve nicely giving you a slightly bluish solution.
9.8 mL of this solution is necessary to bring 100 Liters (26.4172 US gallons) of tank water to 0.1 mg/L copper. Therapeutic range is ~ 0.15 to 0.25 mg/L, but I would try to stay below 0.20 for sensitive species. Can easily be measured with
Salifert copper test kit.
^^ The above
might be an option to try for those struggling with commercially available copper products.
It is "old school copper", which isn't used much anymore (except by public aquariums, research institutions, etc.) because it isn't very "user friendly" and has a narrow therapeutic range. So be sure to pay
close attention to detail when mixing everything & dosing. I will begin looking for online sources to buy the above listed ingredients;
@Randy Holmes-Farley might already know of some.
