When I lived in Hawaii, I took the paint off 14 Luxfers with peeling, chipped paint from my charter operation. I tried the caustic strippers, but those things burn if you get it on your skin. And even if you're careful, you're still going to get some on you.
Then I found 3M Safest Stripper. It's a thick glunky stuff that you could conceivably smear all over your arms and not get burned. The thing is that you have to smear it all over your tanks and then cover them with some thick plastic sheets and let them sit at least overnight. Then take a scraper and start peeling away.
You're going to wind up with a mess of scrapings so watch where you do it. After you strip your tanks, don't bother repainting them. The aluminum is pretty happy without paint. Plus any dive shop that suspects a repainted tank might not want to fill it.