Otherbarry

Hello I'm looking for someone's opinion on what to do. My hot tub is just over two months old and I use bromine granules as a sanitizer. I live in canada so I had no salt starter and my warranty for the spa states I cannot use a floater. I was doing ok for about 2 months and these past 2 weeks have been bad as I cannot keep bromine in the spa for 24 hours even after shocking with about 25gs the level has been 0 the next day. The spa is used about 20 mins a day on average and I clean the filters weekly and change monthly. Should I just drain and purge the spa and switch to chlorine? 1250 liter spa Ph 7.4 Alk 80 Ch 300