I typically only cook meat so I don’t have the problem. However, this is what I’d probably do:
I sous vide in a 12 quart Cambro with a plastic lid. (Insulates and eliminates most evaporation.) My plan would be to vacuum seal a bunch of ping pong balls and lay it across the water surface and put the lid back on. Anything that tries to float will be kept submerged by the bag-o-balls and lid.
I’d wash the sealed balls and store for reuse.
