1 year should be ok.
use betta box, observe for 4-7days
if have brook, it should surface during that period of time. observe closely.
yes i do adjust the pH, but if i did remember correctly, i didnt adjust the temp and pH at the later dips.
but still, dun take chance, adjust it. its rather easy if u got the buffer and equipment to do that.
and always aerate vigourously.
all the best for ur next batch.