My hydro shop has these awesome little rubber fittings, they are like grommets but longer, you drill a hole down low in your bucket and stick one in, then you run in your line and it kind of pushes the grommet and expands it. No leaks.
You can also look for a place in your area that sells "John Guest" fittings, they make awesome bulkhead unions, ZERO leaks. Pricey though, but they are nice push connect.
By the way, that is going to be a royal pain in the ass to maintain water levels, fill and drain with nutes, and check and adjust ph often. You're better off doing some kind of system with an external reservoir like e'n'f, aero, etc.