I already made the Simple Syrup. So what I plan on doing as soon as my new kit comes in...
1. Take the SG with the Kit and water just under 5 Gal mark in the bucket.
2. Add 3 Cups of the Simply Syrup which was made using the 2 to 1 method.
3. Add the water to the 6 Gal Mark.
4. Cross my fingers and hope I am 1.09 - 1.095, if not...
3. Add additional small amounts of syrup or water as needed to adjust.
I will be back to let you know what happened.
Good plan. Note that if the volume is a bit high, it's not going to have a noticeable impact on the final wine.
Two suggestions -- first, add the 3 cups syrup when you put in the concentrate. Sugar doesn't dissolve easily, so the more stirring you give it, the better it will mix.
Second, fill the fermenter to 5-3/4 gallons, stirring as you fill, then check SG. If it's low (which is unlikely with 3 cups sugar syrup), you can add more syrup. If it's high? You're adding another quart of water, which will reduce it a bit. The amount of sugar you're adding should put you in an acceptable range.
I did a test a while back, preparing a must one day, checking the SG. In the morning, stir again and check the SG before inoculating.
Nine times out of ten, I got a different reading the following morning, sometimes high and other times low. Often times it was only a point or two, but on a few occasions it was nearer to 10. This was not only kits, it was also grape wines. This told me 2 things:
1. I don't always stir the must as well as I think I did.
2. No matter how much I stir, further melding is likely to occur. For concentrates, the mixture becomes more homogenous as bits and drabs of non-integrated concentrate dissolve. For grapes or any fruit? Sugar leaches from the fruit AND not all fruit in a batch has the same brix.
Checking SG again in the morning after a stir, before inoculating, gives you the most accurate reading.