My notes tell me this:
Don't use white corrugated hose for below water hookups. What you want is the most reliable stuff available. Only the best.
Use USCG, SAE J2006 R or R2
The best is silicone blue or, 2nd, EPDM black exhaust hose.
Auto hose has no standards.
Mass marine marketers carry Trident hose. But you probably will have to search for the silicone - which has a 10 year guarantee on it! For the few feet we need, it'll be worth every worry-free cent. Yeah, dollar.
I will use the same heavy smooth wall R hose for the blige pump pickups.
'Soft' refers to (2, 4, 6) multi layer polyester or fiberglass reinforcement - so that it doesn't collapse under pressure or bending. 'Hard' refers to spiral reinforcement of plastic or steel wire.
If you use steel wire reinforced hose on bronze fittings, you are asking for trouble.
You may find cuffs for corrugated hose ends that will allow an easier slip fit over hose connectors.
And for thick hose you may have to use s.s. T-bolt clamps.