PLEASE HELP. 2nd BROWN SLIME IN 6 months

[Sir Chris]

So6 months ago I got slime on a green rainbow Acan. Cleaned the one head thought I got it. Nope. Killed the whole colony. Now my red got it and it's 6 months later. I alls removed the green when he 1st head was getting it as I seem it being more of a parasite jumping 2 one 2 other head. So now I cut he bad head off. Was in far corner and tried 2 get as Much flesh off from old head as possible. Was thinkn a copper treatment but that suiside but if it's goin 2 die I wanna see if it could as I feel it is a parasite

 

[Sir Chris]

That's the remainder from 1st encounter with it I figure get ride of the whole head and possible problem