"UNDERWATER" auto white balance on Sony FX3...?

Has anyone used the underwater auto WB feature on the Sony FX3 (has a fish icon on it).  I tried it in the pool and it seemed ok, but the manual WB is noticeably better.  

I shoot on an A7SIII, which to my knowledge the FX3 is pretty close to. Underwater AWB works decently well with good natural light, but it makes for a real pain during editing as your WB is shifting between shots or even in the middle of a single shot. Recommend sticking with manual WB and setting one of your custom buttons to easily access and re-WB often. Also, I bring down a grey card to help pull good WB.

Thank yoU!  - I got tired of dragging the card around so I bought some white fins for quick/hands free WB.