OMG!! that is going to be monster cool!!! and yes, water proofing WILL be the death of you.....LOL can i assume that that china cabinet has a shelf under it, so it is divided into 2 levels? if so, why not build a plexi or glass tank to go on the shelf, thereby utilizing the bottom of the top portion as your false bottom?? i would definitely look into marine epoxy for waterproofing the glass section. i know i have seen one of these type conversions around, i'll see if i can find the thread whilst i surf this evening. Man, i have so many ideas running through my head on this one. and i can point you to THE MAN when it comes to driftwood. has the best manzanita in the states and his prices are excellent. oh, and if you decide not to do this, i might drive to you and steal that cabinet from you....LOL