How to add second hard drive to working QNAP TS-230?

[dleiber]

I have an existing TS-230 NAS with one Seagate Ironwolf 4TB drive. It's been working for a few months. I have a 2TB WD Purple Surveillance HD from my previous QNAP TS-128A NAS. Can I add the 2TB drive to the TS-230 even though it's not the same type/size as the 4TB? I don't need RAID. I just want more storage space. I'm a novice. Any tricks to doing this? Thanks.