The 1980 paper Laboratory Comparison of the Effectiveness of Several Algicides on Isolated Swimming Pool Algae by R.P. Adamson and M.R. Sommerfeld came to the following conclusion:
It was noted earlier in the paper that "The major component of the active ingredients of Algimycin (poly[oxyethylene-(dimethylimino)-ethylene-(dimethylimino)-ethylene-di-chloride])" which is Polyquat, but it also contained some simazine.In summary, results of a laboratory evaluation of the effectiveness of several types of readily available commercial algicides on isolated swimming pool algae demonstrate that at manufacturer's recommended concentrations only chlorine was algicidal to all four species tested. Quaternary ammonium and the silver-containing compound (Algaedyn) were, however, algicidal to the blue-green algae. At higher concentrations (4x recommended concentration), quaternary ammonium became algicidal to the green and yellow-green algae, whereas Algaedyn did not. Algimycin was algistatic to the green alga and exhibited little capacity for controlling the bluegreen and yellow-green algae. The copper-containing compound, Bio-Gard, was ineffective as an algicide at recommended concentrations, since it was not algicidal to any of the test algae and was only algistatic to the yellow-green alga P. pyrenoidosa. Further studies are anticipated to determine whether similar results are obtained for these algicides under actual swimming pool conditions.
Note how chlorine was the most effective algaecide against all species and the product used was Trichlor. However, the way the experiment was done, the active chlorine concentration would be too high since there was no initial CYA in the water. As with the earlier Adamson/Sommerfeld experiments, the experimental method left something to be desired.
The report Effectiveness of a Chelated Copper Algicide on Algae Grown Under Differing Water Column Phosphorus Regimes showed that 0.4 mg/L of copper was effective while the paper Algicidal effectiveness of Clearigate, Cutrine-Plus, and copper sulfate and margins of safety associated with their use showed that around 0.06 to 0.2 mg/L was effective depending on product (the lowest was copper sulfate which is not chelated so that makes sense). Of course, the main risk with copper is metal staining of plaster surfaces and turning blond hair greenish so one must carefully control the concentration of copper and the pH when using such products.