You can buy a flush kit and add it yourself.
Although I use three 150gpd membranes (450gpd unit) and it isn't that expensive to replace the membranes. I've had my unit four years now and I've only replaced them once so far and I use a booster pump. Water goes in at near on 300 and comes through at 006. I top up/ refill the ibc once or twice a week depending on work load.
Isnt that easier than leaving a 150gpd RO on constant