DMS & 90 Min boil in a 7.5 gal kettle

[KyGooglenerd]

I'm planning the Cottage Saison for my 4th of July brew session and am new to pilsner malt brewing. I read many places on this site about 90 minutes boils for pilsen dominated brews and wanted to ask a technique question.

I have a mash tun cooler and will mash and sparge there, but my boil kettle at 7.5 gallons is a bit short for a 90 min boil to get my target 5.5 gallon cooled wort finish. I'm using beersmith to help with the volume calcs.

My thinking is to do a mash/sparge to get about a 6.5 gal preboil, and then do another smaller sparge (about 1 gallon) to get the 7.5 gallons I need for a 90 minute boil or just sparge the correct amount first but hold about a gallon back and add this smaller volume mid boil at some point. I have 2 burners so it won't be a problem to get the 1 gallon top-off to temperature before adding to the main boil so as to keep the boil rolling.

I guess my main concern is hop utilization doing this but since the added volume is small it's probably not going to effect it that much and I would add it as early as possible in the boil.

Or another option is just to top off in the fermenter.

Any thought on a mid boil addition of second runnings for a 90 min boil? Thanks!

 

[ThickHead]

Mid-boil addition of your second runnings would be the way I would go. however, I would bring the second runnings to boil prior to adding them to the main boil. Your biggest issue will be volume-related otherwise as your boil-off rate will be a challenge starting with the 7.5 gallons. You will also lose volume during cooling and to trub-loss depending on how you are calculating final volume to the fermenter.