Xenia will go everywhere eventually. Something will dislodge it in your sump or it will get crowded where it sits and a polyp will let go. The return pump will shred it and distribute the peices all over your display where they will settle on rocks, glass with Coraline, and even on top of zoas and monties and very quickly become new colonies.
New reefers like Xenia because they are resilient, grow and spread quickly, and their natural movement is very pleasing. Advanced reefers hate them because they are resilient, grow and spread quickly, and their natural movement isn't any better than any other LPS or softy.
I enjoyed it in my own tank for about six months when I was getting started and then it started to smother a really nice zoa garden I had going. Then I fought it for another 6 months. Every time I tried to save the zoas by cutting the Xenia back peieces would get loose and I'd have more Xenia. The only way I got rid of it was my tank matured and I got phosphates and nitrates very low and kept them there and the Xenia eventually melted away. Xenia like phosphates and nitrates, that's why it thrives in new aquariums. So do macro algae. That's why we like it in our sumps. If you're having trouble keeping algae in your sump you might have trouble keeping Xenia, too. Good for you!
Use a grow light in your sump, and not just a cheap CFL bulb. I get good results with a $25 LED grow bulb I found on Amazon but a cheap CFL will not compete with your expensive lights over your display. You might also try cleaning out your sump to get rid of as much of the GHA as you can and start fresh with some clean cheato from Algae Barn. It's worth it to make sure there is no GHA or pests hitchhiking in the new cheato.
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