Today I pressure tested the starboard fuel tank. The ballon had deflated since yesterday evening, so I repressurised it, and sprayed soapy water over the rivet lines and joining surfaces and found no leaks, apart from the ballon where I taped it down in an attampt to seal it. I then cleaned all the sealer from the outside of the tank on the rivet lines and rechecked, again the only leak is at the ballon.
Tomorrow I will recheck it again as I've tried to seal the ballon more effectively this time. If it's o.k. on to the port tank!