The account’s monthly closing balance (excluding interest) must have grown by at least $100 compared to its opening balance.

1. Is this the correct use of the word 'compared'? To use the word 'compared' I feel like the opening balance needs to do something, like how the closing balance has grown.

2. Is there a better word to use or way to say this? Would 'from' work?


Your overall approach seems clumsy to me. I'd reword like eg this.

eg The account balance must have grown by at least $100 (excluding interest) in the last calendar month.