too much vacuum???

[kevins maple assistant]

My son and I started producing this year in a pretty big way for a beginner. We are in Southern Ohio and installed 411 taps on 3/16 tubing and 26 on buckets. We tapped the first week of February when our forecast looked favorable but after a few days things changed substantially and we went into a 3 week frozen period with nothing until March. We have collected a lot of sap and made about 80 gallons of syrup so far but have been a bit disappointed with our boil and yield rate and have had to dump several hundred gallons of sap each for a few days. We have 80 to 100 feet of drop on our lines and put gauges on 4 of them with 3 at the top and one on a line that we teed about 2/3 of the way up the hill. All of the top gauges read 30+ inches of vacuum consistently and the one in the teed line 28.5. Our Sap hydrometer was broken at the beginning of the season so I don't know the sugar content at the outset but last week our reading for the sap on tubing was 1.0 Brix and for the buckets about 1.5. I had noticed a considerable reduction in yield rate of syrup from sap as time went on but thought this low sugar content of our sap may be unusual. We did not tap red maples. We have also had quite a bit of sludge in our evaporator and have to drain it about every 1500 gallons of sap and clean it out. We have some sugar sand build up, but this is more like a mud layer.

So my question is can we have too much vacuum which reduces sugar content and can this actually be pulling soil trough the tree roots to create the sludge. Our sap is clear and we filter it going into the tank.

[DrTimPerkins]

So my question is can we have too much vacuum which reduces sugar content and can this actually be pulling soil trough the tree roots to create the sludge.

Over the course of several days the sap sugar content for trees on vacuum will slowly drop until there is a refreeze to recharge the tree system and stimulate more conversion of starch to sugar. So you could be getting somewhat diluted sap, however the alternative without vacuum is NO sap and thus no sugar. In general however, if you are getting a freeze every couple of days you won't see any difference in sap sugar concentration.

No, vacuum will not pull solids (sludge) through the root system. Roots have a tissue area called a "Casparian Strip", which forces water to go through the cell itself, rather than just through the cell wall. Solids cannot penetrate through this area, only dissolved materials.

[kevins maple assistant]

so is the sludge we are getting normal?

[Clinkis]

so is the sludge we are getting normal?

Yes it's normal (at least for me it is). I get lots of it. I get a greyish foam form when I'm boiling and a greyish slimy sludge in my filters. I also get that hard buildup on the bottom of my syrup pan on my evaporator and have to drain it and clean it out a few times a season. It seems worse this year and I've been blaming it on the fact that I've been running a higher concentrate from my RO but not sure if it's just the year.

[brookledge]

Never can have too much vacuum.
Keith

[maple flats]

Vacuum is good, higher vacuum is best. The sludge you describe is just another form of sugar sand. A couple of years I've even had so much, that I sat up a little pump to pull it up off the bottom of the pan, run it thru a cone filter attached to the outlet hose, and run it back into the same channel. I don't know why the sugar sand has so many forms, but you just tackle what you get.