Adding dextrose to the primary...do I still need to control the temperature?

Ingredients
1

My recipe calls for 1.5 pounds of dextrose to increase gravity.  Rather than adding it to the boil, I’ve opted to add it to the fermenter towards the end of primary fermentation.

I have my batch split into two fermenters, one with 1318, and one with 1098.  I kept both around 65 degrees for the first 3 days and then started letting them free rise.  Right now they’re both at 68 degrees and nearing the end of primary fermentation so I am planning on adding the dextrose directly into the primary.

My question is do I need to be concerned about the temperature rising even more when they yeast start eating the dextrose?  With only three quarters of a pound in each fermenter, I don’t think the yeast activity will create enough heat to hit the upper ranges of either of these yeast. However, I also don’t like going anywhere near the upper ranges until the very end of fermentation and since I’m adding dextrose it seems like restarting the primary.

Thoughts?

2

You might get a modest temperature boost if the yeast are still very active.  Bear in mind that unless you are at high alcohol levels, the yeast can tear through sugar pretty quickly.

3

I think that’s enough sugar to produce a fast and vigorous fermentation that could move the temperature up a few degrees. I would control the temperature with the addition. No risk of harm controlling temperature, only risk in not controlling.

4

+1. If you can control the temps, then why not?

5

Only reason would be that my typical process would be to ramp up the temp after primary is winding down to ensure a complete fermentation and as much cleanup as possible.  I guess in this case the adding of dextrose is essentially restarting the primary so I’ll delay the ramping until it slows on the dextrose