For floating plants elodea densa is my go to, grows like crazy and you can just snip it off when it gets too much. Other low maintenance floating plants include water lettuce and frog bit.
Just watch out for pest snails, I feel like they're inevitable at some point when buying plants unless you just buy bulbs!
Just watch out for pest snails, I feel like they're inevitable at some point when buying plants unless you just buy bulbs!