if you have got one give it a try ,i bought a second hand booster pump off e bay for twenty quid and it does not look much different to a flojet or surflo,just make sure it does not run all the time,i use a timer plug with every other segment on so it gives 15 mins on 15 mins off this has really made a big differnce to how quickly i can produce water and how efficient the set up is
Done it with a 100psi shurflo and didnt work .... sorry to be the bearer of bad news
Did the same as blue frog 100psi shurflo 100gpd ro , no pressure switch ,.......DID NOT WORK !Rich