Buckeye Hydro
Active member
For softened municipal water, and an RO system with 2 to 4 4040 membranes plumbed in series, a good rule of thumb is to set the concentrate to 3+ gpm and set the recycle for half that amount.
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Upgrading an RO system
- Thread starter OurTown
- Start date
OurTown
Well-known member
Wouldn't the downstream membranes get really high TDS water, especially the last in a series of four? Is the recycle the amount of water going back to the pump inlet? I don't think our system does that because it just has reject and product water flow meters.
Buckeye Hydro
Active member
Yes they would - that's one reason it is so important to pretreat for scale forming minerals like calcium and magnesium (aka hardness).
Yes - "recycle" refers to taking some of the concentrate and routing it back to the intake side of the pump.
Some lower-end RO's include a recycle function without a recycle flow gauge... but you are correct - you would want a flow gauge on the recycle.
Yes - "recycle" refers to taking some of the concentrate and routing it back to the intake side of the pump.
Some lower-end RO's include a recycle function without a recycle flow gauge... but you are correct - you would want a flow gauge on the recycle.
Buckeye Hydro
Active member
If your demand for purified water is low enough, also consider using multiple 2.5" diameter membranes - where the minimum recommended concentrate flow is 1 GPM rather than 3 GPM for the 4" membranes.
