I have the same problem with my red and purple people eaters. All over my rocks and glass in 3 tanks. I think I scrape off about 50-100 polyps every few weeks and just dump them in the trash.
the only real option is to manually remove as many as you can. This typically menas taking a large chunk of rock out of the tank and scraping off the zoa mat. You can keep the large pieces and trade them. That is the drag with Zoa and GSP they are like a weed - just prettier
seriously??.. what kind of PPE do you have?.. and why aren't you just trading them or selling them??... heck, I'll take 'em and gladly pay for shipping and handling... PM me.. lol..
btw legit PPE?? because I've seen variants and morphs of PPEs.. the true PPE takes forever to grow!! Thus why they still fair expensive...
it is through ... keeping one's hands out of their tank ... that will produce growth.