Leaking bulkead solution?

[Reef Pilot]

You are really asking for trouble if stay with the nut on the plywood side. You might get it tight enough to stop leaking as you keep taking up the slack with the weight of the water settling. But in future if the wood swells due to humidity (a very likely scenario) the glass could crack, and then you will have a very costly mess. And did you say you are in an apartment? I yi, yi,...