Scales and green stuff in aluminum tank

[hd002e]

I have about a 3 inch opening atop my aluminum water tank and upon a recent inspection i found some scales and green (guessing algae) growth. I remember aluminum reacts with some common household cleaners and want to make sure I dont punch a hole in the bottom of my 600L tank. How should I go about cleaning it?

I am not concerned about the scales as long as I don’t have a full on bacterial/algae colony posing a biohazard in my tank.

Thanks friends!

[hd002e]

Now with attachment

[skipperpete]

Algae might be the least of your problems, get a shopvac and clean out the “scales” to see how deep the pitting really is.