Go to
www.por-15.com they have a product called marine clean that works pretty good. They also have a product called US Standard that is supposed to be a good tank sealer. I doubt you would have a problem with it clogging your pick-up if you follow their instructions. In regards to the sender. I could not find a replacement for mine so I put in a (I think) VDO adjustable sending unit. I had to re-drill the mounting holes but otherwise it was a perfect fit. Came with everthing I needed for the indstall also.