Am I pulling to High Vacuum?

[kiegscustoms]

We are able to pull between 24" to 27" of vac on the entire bush. I noticed that the sugar content had been very low this year. I know it has been somewhat diluted by all the snow but my question is am I stressing the trees out too much by pulling too much vac that the sugar can't keep up with the sap flow? I have been averaging 1.6 sugar this whole year. Saw 2.2 once this season for a high and 1.3 for a low. Any input would be great!

[danno]

Studies show that high vacuum does not negatively impact trees, but I do believe it reduces the sugar content in the sap. BUT, the volume of sap collected due to high vacuum outweighs the reduction in sugar %. At least that's the theory I like:)


We are able to pull between 24" to 27" of vac on the entire bush. I noticed that the sugar content had been very low this year. I know it has been somewhat diluted by all the snow but my question is am I stressing the trees out too much by pulling too much vac that the sugar can't keep up with the sap flow? I have been averaging 1.6 sugar this whole year. Saw 2.2 once this season for a high and 1.3 for a low. Any input would be great!

[kiegscustoms]

It would be great if I had an ro. I have been boiling as fast as I can but cant get any light syrup. Got a boat load of sap but would almost rather have less with higher sugar content so I could get some lighter syrup. Would a vac regulator help at all?

[DrTimPerkins]

am I stressing the trees out too much by pulling too much vac that the sugar can't keep up with the sap flow?

No, vacuum (low, high or anything in between) doesn't harm trees. The wound is not bigger, it doesn't rupture cells, it doesn't move ice around in the tree and cause damage, or anything else bad physically. It doesn't cause slower healing of the taphole either.

What vacuum does do is remove more sap and more sugar from the tree though.

Does it dilute sap? Somewhat more complicated answer there.

1. If the sap would be running normally under gravity, then you'll get the same sap sugar concentration under gravity and vacuum.

2. Once the sap stops running under gravity (meaning that if you were on buckets or tubing, you'd stop getting sap), then you start pulling sap from a larger area within the tree. Initially this sap is pretty close to the same sap sugar concentration as the sap under gravity.

3. If it doesn't refreeze for an extended period (after a couple of days), then you are essentially pulling water out of the soil, through the roots, up the stem and out through the taphole. It has less time to interact with the tree and pick up sugar. In that case, the longer it goes without a thaw, the more dilute the sap will be. However....without the vacuum, you'd get NO sap and NO sugar from the tree, so you're still coming out ahead. If you have an RO, it isn't much of a concern. If you're boiling raw sap....then perhaps it is.

4. Once it refreezes, the flow (and sap sugar concentration) regime goes back to #1.

[Edward Howell]

We are finished in WV , and had a lot of rain and warm weather , my sugar content finished at .666 % . 31 gallons syrup on 4200 ga sap.:cry:

Only pulling 15 vac,

Tx ED

[CBOYER]

.666% is a very bad number:mad:

[kiegscustoms]

Thanks for the info Doc. Great having you on this forum to give us some reliable researched knowledge. I have kept in the back of my head the post you listed with the videos of the vac. manifolds about sugamaking similar to a mental disoreder, things freezing and breaking and fixing them and then waiting for the sap to run again ready to burn the sugarhouse down etc.... That has been my season to a T! I have been making primarily b to commercial off the 1.5 sap we have been getting this year . I have also noticed an increased amount of sugar sand. I would expect to make 20+ gallons before having a niter build up (enough to cause concern) before having to do a pan swap, but I have a hard time getting 10 -12 this year. Could that be from drawing the extra water out on the days without a good freeze? Also, this last few good runs we had the snow was melting very rapidly with the 2 days in the 60's, could the sugar content go up with the projected forcast not reaching above 45 with a good freeze at night?

[3rdgen.maple]

We are finished in WV , and had a lot of rain and warm weather , my sugar content finished at .666 % . 31 gallons syrup on 4200 ga sap.:cry:

Only pulling 15 vac,

Tx ED

All I can say is WOW Just when I was feeling sorry for my 1. 4 to 1.7 I see this. Thats alot of boiling for 31 gallons. Got to take what nature gives us though.

[syrup2nv]

It seems as though our sap is getting better! The season started out averaging 1.8. The past couple of runs have averaged 2.4! All last week we were on the B Train, though now were making A Med! As of tonight we are up to 165ish gallons! Looking better than last years 140.

[kiegscustoms]

That's reassuring! I made 20 gal light B on monday, no run until today and the releaser was dumping every 2.3 - 3 minutes (dbl vertical mechanical). During that 20 gal went from just a little darker than b to almost dark amber. Havent checked sugar content yet tho. Maybe things will turn around, just kinda seems backward...:confused: