Minimum balance for ALGO
ALGO is a special asset that requires a minimum balance on the address. Every address should have at least 0,1 ALGO on the balance.
If you will send out a transaction that will result in a balance lower than the minimum (0,1 ALGO), that transaction will fail. For that reason, Atomic Wallet blocks 0,1 ALGO on your balance so that the address would stay permanently activated and ready to use. Thus, your available balance for ALGO always excludes 0,1 ALGO from it.