I think you will defineatly have to buy a booster pump, those aquasafe units seem to be real fussy about pressure. DO NOT buy one from one of these outfits in red deer. check out
www.purelyh20.com the booster pump will run you about $100 (as opposed to $300 here in red deer), a new membrane in the 75 gpd flavour will cost you about $30-$40 with the flow restrictor and flush kit (highly recommended). Make sure you insist on USPS for shipping otherwise UPS will whap you with a big brokerage fee. If you need DI, littlesilvermax is the guy to grab it from!!
Also, if your turning the source water on and off all the time, that may be hard on your membrane as well. Your aquasafe should've come with a pressure switch that turns the water on and off automatically without letting the membrane dry out.