booster pump and ro/di

hey guys.
i got SpectraPure® Maxpure RO/DI System- 90 GPD connected to my shower faucet and got 45-55psi from it,because my wife didnt like it too much i installed unit under the sink.i used tee conector on my cold pipe and with my solenoid from autotopoff i got only 10-15psi!so i eliminate solenoid and got 15psi.today i got my booster pump aquatec 8800(installed between source and rodi) and i got 20psi without solenoid.am i missing something??why pressure is still so low??

 

Try unscrewing the pressure gauge, adding a few wraps of teflon tape and screwing it in not quite so far. Sme gauges bottom out in the housing and do not read correctly.

If you had 45-55 at the shower you should have the same at the sink unless you have plumbing issues.

 

i got it.didnt know that waste yellow pipe(with tinny one in it) got to be connected,i just use regular 1/4 tubing and it looks like it loose all pressure.now i got 45psi and with booster pump 80-90,unit will be more effective with so much pressure or i dont need pump?

 

The yellow waste line has the capillary tube flow restrictor in it.
Take the time to read the instructions then time and measure the waste ratio and trim the flow restrictor to 4:1 if needed, this is a critical step.

Spectrapure has a spreadsheet somewhere on their site that shows how much efficiency you would gain with a booster pump, not sure exactly where it is though.
Off the top of my head I suspect you would gain 1 to 2% rejection rate boosting it from 45 to 90 and you would also go up from about 60 GPD to over 120GPD with the same RO membrane. The 1 to 2% increase in efficiency would make your DI resin last 75 to 100% longer so cost less per gallon to make and the increased GPD means less standing around waiting for treated water.