Acoustic guitar string tension?

I have had the same problem for years. I took my guitar to the Guitar Center in Nashville. I explained them the problem, so the tech repaired it. He told me that he filed the bridge for lower action. He used the lowest guage, but he told me that the unwound strings are plain steel that's basically the same as electrics. He put slinky 09 on the low and what ever he did with the B and s. It plays perfect.