youd be surprised the dent 1 gibbi let alone 2 will put in that size chunk of cucumber overnight. water will be fine as long as you remove any uneaten within 24 hours . you will need to weight the cucumber down with something as it is bouyant i use aquarium lead like they bunch plants with in most lfs failing that ive seen people stick a fork in it. i just cut off a chunk take a strip of peel off it ( altho its usually eaten from the end ) weight it and put it in just before lights out