Hi Bolas... First I want to say: congratulations for your rig Looks nice, but I donīt like to much what you did with the FANS on the top rad. It looks to me like a sandwich with the rad in the middle. jejeje (But is just my opinon).
My advice with the leak test is: you can use towel paper and plastic bags to cover all critical hardware. I better than paper only

Oneīs again... congratulations for your rig