When to add Galaxy and Mosaic

All this assuming this is a 5 gallon batch.

Personally, I love mosaic in boil and DH/galaxy in DH. A lot of galaxy can get weird quick. 3.5oz is modest which is great. I would:

.5oz mosaic @ 60
1oz mosaic @ 15
1oz mosaic @ FO
1oz mosaic/3.5 galaxy @ DH

DH being one charge when fermentation is done, soft crash your yeast, and DH temp at 55 to 60*F.

 

Galaxy DH for sure. Don't use mosaic so don't know.

 

I don't know the alpha acid content of each of those hops, but I've always been told the higher AA percentage should be used for the bittering hop.

The relative taste dominance of one hop over the other would only be considered for the later additions because minimal to no hop flavor will be available from any hop that has been boiled for 60 minutes. The flavoring hop choice is personal preference, and that choice is tricky.

 

Definitely don’t use Galaxy at the beginning of the boil. Like most of the other Aussie hops the resulting bitterness will be very rough. I believe it’s caused by the very high polyphenol content in those hops.

Personally I wouldn’t use either of those hops at the beginning of the boil. You don’t necessarily need a charge at 60 minutes. If you want to, just add something clean and neutral that maybe you have on hand? Warrior, Magnum, Nugget, columbus, Chinook, etc.

If you only have those two hops Mosaic is the one to use at 60 without a doubt. The schedule that was already provided is similar to what I would recommend as well.

 

In addition to doing exactly what @wasatchback said, I recommend using software and learning how these hops effect overall bitterness. Have a bitterness target and build your hop schedule to match that target. That's the best way to know how to adjust recipes to suit your taste. Some free ones are Brewers Friend and our own Brewcipher. Yes, there will be a learning curve, but such is brewing.

I tend to skip a mid-boil addition and just whirlpool for flavor. The last time I used these hops I mixed them 1.5:1 (M:G), with a moderate amount in whirlpool and a touch more in DH.