Hah
That made me laugh, had exactly the same issue with water lettuce in my 3 foot tank.
Went on holiday for 10 days, came back, entire water surface was covered in water lettuce, and I really do mean every single bit of surface!
And that’s despite me leaving a small clump of water lettuce in corner, about size of my hand before I left!
Chucked out loads by the handful and looked as nothing else was affected, livestock were happy enough and root plants showed no issues from lack of direct light from light unit for presumably a few days.