Borates are reduced by overflow/draining, carry out and splash out. And assuming you are in Nashville, Michigan or Nashville, Illinois then you will lose quite a bit when you close your pool. If you are in Nashville, North Carolina or Nashville, Georgia you may not need to close your pool and lose borates. Use Poolmath to calculate how much borax and acid to add to get back to your target level. Adding just borax is not the right way to do it and will impact PH.
You can add your state to your profile and it will show up over there <-----.