After maple season I am going to try and make birch syrup. Given the significantly lower sugar content of birch sap, I want to consider a couple methods to increase the sugar content. Basically, I am trying to find out how to maximize the sugar content of the sap and thereby minimize the boiling needed.

Maybe this is a stupid question, but if I use an RO (e.g. RO bucket) there is a sap input and two outputs, one for water and the other for concentrated sap. Should the concentrated sap go into a separate container or feed it back into the sap input container?

If I capture the concentrated sap into a separate container and then repeat the process, how many times can I pass the sap concentrate through the RO before it stops extracting water? In other words, what is the maximum sugar content that can be achieved using an RO?

When maple sap partially freezes, it is my understanding that the hunk of ice floating in the bucket is just frozen water and the sugar is left in the bucket. Although birch season is when nighttime temps are above freezing, I might have access to a freezer. After I maximize sugar content to the greatest extent possible with an RO, would I be able to increase the sugar content further by partially freezing the concentrated sap and scooping out the precipitated ice?

Is there anything else I can do to extract water from the sap and thereby increase the sugar content before I boil?

Thank you

Edward
Massachusetts
2021: 12 taps on buckets (1 tap per tree)
200 gallons of sap (had to toss 40 gallons)
4-compartment evaporator (17”x23”)
4 gallons of syrup