I had a 240G FOWLR with a few ASM skimmers and lit with MH. I used sugar to keep the N and P in check before dosing carbon was "cool." I changed 44G of water ever 2 weeks (50G bag of IO). The purples and the black tang is currently in 1800G tank in a local hospital along with an ex zebra eel, volition lion and chocolate tang. Now that you mention it, I have no idea what happened to the hybrid after he got too big.
Most of these tangs were 4+" (real 4", not a live aquaria 4" that is like 2.25") and were given to me as known coral eaters - even the black tang. I purchased the hybrid before hybrids got cool. I caution people all the time to keep their tangs fed - most of these would demollsh polyps and LPS.