CaCl2 kills algae on leaves?

• pH: 6.7
• Temp:
• KH: 5
• GH:
• NH4:
• NO2:
• NO3: 5 (before dose)
  
• PO4: 1.0 (before dose)
  
• Iron:
• Dosing: 2 tsp CaCl2 (5 mL Flourish, 0.5 ppm iron chelate yesterday), 10 ppm NO3, 1.2 ppm PO4
• NO3:PO4 Cumulative Dosing Ratio: 28.5:3.6 = 7.9

Notes:
There seems to be depressingly little growth in the plants (except for the algae, of course, which is flourishing. This week, the green hair algae seems to be the star grower). Whatever is growing from the Rotala rotundifolia/indica is very stunted. In desperation, I added 2 tsp CaCl2 to see if that would make any difference. I've tried everything else, it seems.

An interesting observation I saw is that when I added the CaCl2 flakes into the water, many of the flakes fell on top of the anubias leaves, some of which had this very tough dark green/black algae dotting the leaves. Wherever the flakes landed on top the algae, the algae turned a brown/red color within a few minutes and even disappeared from the leaf, as if it had died. Interesting. I took a picture of it, it's hard to see through the green dust algae growing on the glass, but I circled the leaf where it's most apparent. You can see the cleared patches ringed by the red of the dying/dead algae (along with some fish poo).

Once I get the general algae problem fixed, instead of dosing the CaCl2 dry, I might try making a concentrated solution of the CaCl2 and use a dropper/baster to drip it directly on the most algae ridden anubias leaves. I know other people have used hydrogen peroxide to kill algae, though I don't know if it would work on this particular type of algae, which is very tough, feels rough, and does not rub off with my fingers. It also dots some of the leaves of the Alternathera reineckii.