Hi, ive been planning on constructing a aqua terrarium for my white's and i wanted it to be a aqua terrarium but im unsure if hydro balls are needed as it will 100% water i was thinking of just pebbles/gravel for the bedding. And also ive bee thinking of getting the exo terra turtle cliff with the filter inside but the thing is i do not have expandable foam so it cant be stuck to the corner, but is the really necessary?