How are you adding grapefruit? The last time I used it, I added the zest of one grapefruit to a 2.5 gallon batch at flameout.
That’s somewhat of a personal preference. I tend to go a little lower, somewhere around 40. I know other people like to go 60-70.
I never use actual grapefruit. You can get so much grapefruit flavor from Centennial in the late additions, it just doesn't seem worth it. Add some Mosaic in the mix and you can boost the grapefruit even more and add a dose of pineapple/tropical fruit.
Just be careful who you give the beer to. Real grapefruit can mess with some medicines (not sure which ones though)
Many, since it interferes with medicine (and some nutrient) absorption. Warn anyone that drinks it. Most of the flavor is in the zest so my advice would be zest the grapefruit, use the zest in the beer and eat the grapefruit.
^^^^^^^ This. I made a grapefruit IPA using only Centennial a few yesrs ago and when it was fresh it tasted just like grapefruit juice. I don't remember the exact recipe, but I seem to recall using 2 oz in a 30 min hopstand and 2 oz dryhop.
I finally add zests of 1 grapefruit and a half. During whirpool, 80 celcius degree. Took it off at day 2. I taste the OG, just perfect at that time. Thanks!!