Algae on growing medium

[LiveLaughGrowOrchids]

Hello all, I repotted a Phal orchid for my mom yesterday(she was worried she would kill it) and found that all around on the outside the sphagnum moss was emerald green with algae. I removed most of the old media, but a lot of the healthy green roots were also this dark green color.

It was growing in a see through container and seemed otherwise happy, was flowering until recently, for about 5 months.

Is this harmful to the plant? Should I have removed all those roots?

I've repotted it in a mixture of moss and bark.

Thanks!