Blueberry is one of my favorites.
5-6lbs of blueberries, frozen, then thawed and mashed into a pulp will give you about 1/2-gallon of mush. This will still be cold, so you'll want to dissolve the honey into the water first. 1 quart of honey per 1 gallon of finished mead.
I usually use about 1/2 - 3/4 of a gallon of water per 5-6lbs of blueberries. This gives me a little leeway for racking losses.
5-6lbs of blueberries + 1/2 to 3/4 gallon water + 1 quart honey = ~1 gallon finished mead
After combining the warm honey-water mixture to the cold mashed blueberries, it wont take too long to reach room temp.
Opti-Red, Booster Rouge, FT Rouge Soft, are all added in my batches of blueberry. Yeast.. I'm still trying to find the best fit for me, personally. I need to make more, lol. Go-Ferm during yeast rehydration & staggering nutrient additions of Fermaid-O or Fermaid-K are preferred.
SG around 1.090-1.095
pH around 3.4
It comes out really lovely, fruity but with depth and character. Lovely aroma, beautiful color. I really enjoy it.