Problem with Milkshake Mango IPA

[kimoa]

Hi Guys!
I brewed a Mango Milkshake IPA 2 weeks ago. I measured OG with a refractometer and it came back as 1.061. I added Mango one week into fermentation at 1.031. Now a week later its gravity is 1.035. Can the problem be the addiction of mango or the lactose? is a refractometer even suitable for this? I should add dryhops in days and I don't know what to do. I used Safale-US05 and it is on perfect 20 degree Celsius.
Thanks for the help!

 

[rburrelli]

Refractometers do not read gravity correctly in the presence of alcohol. A correction factor must be applied. Most brewing software includes this utility. It can be found easily on the net.

 

[Bobby_M]

Exactly right. You can't use a refractometer once fermentation starts unless you use a correction calculator.