I ordered a Nitro duck ireg. with piston kit,i then ordered a Wevo 13 cu. in. tank only. My idea was to install the N.D. ireg on wevo tank.Sounded all simple until i called local paintball shop were i have my tanks filled. He said if i swap reg. to wevo tank ,he would not fill it. He said he was not certified to perform that service . Both tanks are new 3000psi rated H.P.A. Has anyone ever changed a reg. to another tank,if so is it all that complicated ,that you have to be certified. Thanks for any help.