Thanks chem geek,
As an update, I did a 2nd purge and refill using Ahh-Some Hot Tub/Jetted Bath Plumbing & Jet Cleaner. It produced a lime green scum in the foam so I was hoping that this purge would remove any biofilm concerns. I refilled and restarted the chem process by using the Frog jump start system (33% Sodium dichlro).
Low and behold i tested the water this morning again and the bromine was down to almost zero again. I just ordered a sodium bromide product and will try that to set up a sufficient bromine bank.
Stay tuned, will report back