I am designing a hydroponic system and need to control algae. Copper is a known algaecide and lettuce actually needs some copper to grow well. I had read stories about people using copper pennies in things like bird baths to reduce algae. Pennies in the nutrient solution reservoir did not seem to affect the algae much.

I had a thought that by increasing the surface area, I might get a better result. Fine copper wool is available for finish sanding, and I was thinking about running the nutrient solution through that to try to get some copper into solution. The nutrient solution is ~pH 6 and 25C and has the (somewhat generic fertilizer) contents shown below at about a 1g/L (~2000uS EC) concentration. The flow rate is ~4L/min, but only for about a 10 seconds every 300 seconds. Another option is just to leave the copper in the water reservoir so that it is always in contact with the nutrient solution.

Is it possible to get ~1ppm of copper into solution from an elemental copper source in the nutrient solution?

It doesn't matter if it takes a week or so, as long as there is some chance of the copper going into solution.


I found this paper on Cu/Zn soluability vs pH. It contains the graph below.

Is it true that assuming that ‎Cu2+ ions have 63.546 g/mol weight, and 1ppm = 1mg/L, that 0.001g/L * 1/63.546 mol/g => 15uM solution, and thus the graph indicates that at pH 6.5 there will definitely be more than 1ppm of copper in solution at 25C?

enter image description here

Nutrient Label

  • $\begingroup$ Just buy better fertiliser. $\endgroup$
    – Mithoron
    Mar 5, 2018 at 21:46
  • $\begingroup$ @Mithoron Is my question edit sufficient for removing the hold? $\endgroup$
    – crj11
    Mar 7, 2018 at 22:47
  • $\begingroup$ This graph is for equilibrium with hydroxide not metal, also it suggests the opposite of what you state. And my earlier comment still holds... $\endgroup$
    – Mithoron
    Mar 7, 2018 at 23:06


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