post tank crash

xHi all. have a 6 foot by 2 foot by 2 foot tank , with a 48x20x20i nches sump. had a bad crash the other week and killed of all corals, put my fish into the QT tank and did a complete water change tank and sump, followed by a 50 percent water change 2 days later, then 20 percent changes. now my amonia is zero, my nitrites are zero and my nitrates around 0.4.. but i have had a bloom of brown hair algae. i will be putting a yellow tang, a blue tang and a two barred rabbit fish back in... will they eat the algae??.. or will i need some specialist CUC to do the job...
thanks in advance for any input