Originally Posted by
DRoseum
Do no reuse flush water/ permeate. Once you use it, discard of it.
Use MOST of your permeate each day for flushing. It will really help keep your system performing best. If you get 25, use it. If you get 50, use it. Even when needle valve is wide open on a flush cycle, you will get some permeate flowing out. I run that permeate trickle right back into permeate tank i am drawing from to prolong the flush.
Ro soap is NAOH. It's a base solution and there are instructions for how to mix it up before use. Goggles and gloves are a must. Most indicate a PH around 11 (check membrane limits as well). RO bucket and mattatock madness site have good cleaning instructions. Basically recirc that for a while and then flush liberally with as much permeate as you can, ensuring your PH returns to neutral. You won't need to wash daily if you are running your RO with low recovery rates on the membranes (recovery rate per membrane = permeate out / inlet flow) and are flushing regularly with liberal amounts of permeate. Probably a couple washes per season and one at year end is good depending how much sap you run thru it etc.
Initial rinse of new membranes requires a fair amount of water. Be sure to have a pre-filter in your housing. The membrane manufacturers typically specify how long to flush them for when brand new. Most residential membranes say 1 hr. With 3 membranes (400gpd + 2 x 150gpds) in series running 1 hr --> 700gpd/24hrs = 30 gallons...I'd recommend 50 gal or more.