Generic question on Backwash and Rapid Rinse times

[Mauser]

I just finished setting up a new Fleck 5600SXT system, and y'all have helped me a huge amount in understanding various setup parameters and salt efficiency, but I still have two basic questions that I think apply to any typical down-flow softener.

How do you choose best Backwash and Rapid Rinse times? The setup instructions seem to usually say to set both at 10 minutes (my 64K system came with the valve preset for BS=10 and RR=12), but I have noticed that virtually all of the recommendations I have seen on this forum use much shorter times - typically 5 minutes for each.

So it seems to me that a longer BW time of 10 minutes would be a good thing, with the only drawback being slightly higher water use (no downside with a well). Is this correct?

Conversely, longer RR times would seem to just be washing freshly softened water down the drain and wasting total unit capacity, since it happens after the resin has been regenerated. But going too short on the RR setting risks not properly repacking the resin bed after the brining. Is this correct? Is the best RR time dependent on resin tank size, drain valve capacity or any other physical factor?

 

[Bannerman]

The preset BW & rapid rinse settings are generally appropriate and should not be normally altered unless there is a problem.

BW does two things. In addition to flushing out any debris solids that enter the resin bed, backwashing also expands the resin bed so as to ensure the brine has more complete contact with each resin bead. Think about the beads being loosened so that the brine can easily flow in between.

The fast rinse phase is mainly to re-pack the resin bed again so that service flow is forced to flow through the bed as opposed to flowing through the spaces between the resin beads. If any brine remains in the resin bed (there should not be any remaining if the Brine Draw phase is set appropriately), that remaining brine should be also flushed away. The resin bed re-pack should not require much flow time which can often be reduced to 3 or 4 minutes if water usage is a concern.

Both BW & RR flow rates are governed by the DLFC restrictor button that is installed. The appropriate DLFC flow rate is established by tank diameter and water temperature as colder water is denser than warmer water so a higher flow rate is required in areas with warmer ground water.