Need to Top up Fermenter

Ok so today I boiled outside and it was chilly and very windy. I lost quite a bit during the 90 minutes just to boil off.

After cooling and transferring to fermenting bucket I had my desired gravity at 1.070 but was about 1.5 - 2 gallons short. I started getting desperate and trying to suck out the trub from the kettle and siphoning it through a mesh strainer but I'm sure I sucked up a bunch of what I didn't want in there.

Then I thought - I hadn't emptied my mash tun out yet, so about a half gallon of trub and protein filled wort added to another few gallons of water at 170 degrees went back through the mash tun, I let it sit for 10 minutes to shock the grain. I collected a few gallons from it (think I had quite a bit of moisture in there from my first go too) and now I'm going to boil that for about 10 minutes, try and cool it and top up my fermenter with that once cool, then pitch yeast. I'll measure gravity again after mixing both boils.

Do people do this, or is there a better way to get the outcome I'm looking for here? I was thinking of boiling just water and adding that when cooled but that would have watered down my gravity significantly when I want 6.5 gallons fermenting and 2 gallons were just plain boiled water.

 

The biggest risk I can think of is over-sparging which could result in tannin extraction. I probably would have boiled some water and added some DME to make up for the difference, especially if you hit your target OG.

 

Both great points and help.

I followed up and double checked my measurements (when I wrote the post I was flustered and just winging it)

Beersmith had my recipe with a 1.064 at 6.5 gallons .... I ended up after boiling off with 1.073 at just a hair under 5 gallons.

I went through the extra "sparge" and boil and added to fill to 6.5 gallons, let it mix and settle and at the same temperature I now hit 1.061.

So not too bad as far as results.. at the end it will still be beer of course ;-)

I think the lesson I learned is I need a bigger kettle so I can hold more and account for more boil-off