Are your main drain and skimmer line separate, until you tee them together at the pump?

I have dual 1.5" suction lines (separate main drain and skimmer line) all the way to the pump. Dual 1.5" lines would give you plenty of flow, I have no problem feeding my .5HP northstar pump. I have the separate lines coming together at a 3 way Jandy valve........the suction lines go inside the inlets of the valve (1.5") and the feed to the pump I use 2" (mostly because the Northstar has 2" plumbing connections).

If the only section you can replace is near the equipment pad, its probably not worth it. If you have the 2 separate lines, it might be worth it just for operating sake to get a 3 way setup. I find it very useful because I can turn down suction to the main drain while vacuuming, and I can also use the main drain only when pumping the pool down for winterizing.

-Chris