I could probably snatch off a hunk of chaeto if you would like. Mine is really good stuff, but I don't have a huge hunk. I could pull off probably a softball size hunk for ya....Pretty good pod population in it....Let me know if you want to get together for this.
As for flatworms, I have pre-dipped EVERYTHING that goes into my tank with Coral Cure, Flatworm Exit and FreshWater (where appropriate). I have not had them in this tank at all, but if they aren't too bad a little parameter control and selective siphoning and I was able to control them....it generally takes about 3 to 6 siphonings and I got em under control....make sure your nutrients are controlled and they usually will wax and wane....I try to avoid FWE and stuff like that if I can....If you can remove most of your stuff to a bucket, give the rocks a FWE, Coral Cure and FW dip (excepting montipora) and deal with the population in your display. They will get better....
At any rate, drop me a note if you want some chaeto....I'm in Tuskawilla area, so I'm close....