My Friend has a 180gal, he bought 5 out of the same tank at the store, Qt together and put in together. No problems with them over a year now. I think the key is having them together from start to finish. One is a little more dominant but still no problems. You have 220 gal. So maybe work. My .02, not experience just observation. If you try, pick from the same tank and get the shy ones.I have a 220g DT with a 55g sump/refugium that's around 6 weeks old... This will be a mixed reef..Everything seems stable.. I have 4 percula clowns, 1 yellow coris wrasse & 2 blue reef chromis & a mixed cuc. Could I put in 4 yellow tangs & maybe a regal tang ??