I had a bad outbreak of it about a year ago only to find it was caused by multiple problems:
1) Aquarium Lights on too long. I now limit it to 6 hours a day.
2) High nitrates caused by insufficient water changes. Until I joined this forum, did not know to do changes weekly. Went from 25% monthly to 20% weekly.
3) House faces east and direct sunlight was coming in over the "window" above the front door that has no curtain into the side of the aquarium. Solution: Put the same backing on the east side of the aquarium that is on the back side.
4) High phosphates in tap water. Solution: use a mix of 40% tap, 30% RO, and 30% bottled spring water.
The existing stuff is extremely difficult to remove from anything. As for getting rid of it ...... I tried the peroxide rinse and hand scraping but ended up throwing away all my plastic plants, decorations, and filter ...... and starting over.