I like to use a 2" pump, for a while I was running just the water transfer pumps, a bit of research on lift distance and litres per hour and I scored a nice one of eBay for $200 free postage (had to wait awhile for a cheap one to pop up)
Now I tend to use 1 1/2" (40mm) fire fighting pump, a larger amount of pressure, blue lay flat seems to hold up well enough vs the weight and price of the heavier duty red lay flat, the black plastic thread on fittings were good and cheap enough until I had the coin to afford alloy cam locks
Now I tend to use 1 1/2" (40mm) fire fighting pump, a larger amount of pressure, blue lay flat seems to hold up well enough vs the weight and price of the heavier duty red lay flat, the black plastic thread on fittings were good and cheap enough until I had the coin to afford alloy cam locks