RO question (temperature vs pressure)

[mark]

So I figured go buy 50' of 1/4" tubing to use between water line and ro/di unit placing the excess as a loop in the sump. The unit would have a little better rejection ratio because of the warmer input temperature and I would get a cooling coil in the sump.

Just temporarily hooking stuff up see my input pressure has dropped quite a bit to 40psi.

Before I start doing comparisons a rejection ratios, wondering if it's even worth it considering the input pressure drop (in the red on the gauge). Those doing this, did you use large tubing for the sump loop?

Pressure gauge is T'eed just before prefilters.
RO/DI off, line pressure is 55psi.
Unit output open, short feed, input pressure 48psi.
Unit output open, 25' insert, input pressure 43psi.
Unit output open, 50' inset, input pressure 40psi.