70
After like 3 years I was again brewing beer just for fun and not 2000l batch as my job or trying something on this small scale for my job (because I had a time and got the ingredients for free).
It is really experimental brew. I put 3,5l of grape juice (I think it is Veltlín variety) and will add some cherries there too. So let's see how it will end up.
Refractometers start to be really off once you have fruit juice and ongoing fermentation. I use mine only to see if reading is changing over time, absolute value is easily off by 20-30 g/L
I know, it is really handy for checking OG then it gets skewed by alcohol. For bottling I use my hydrometer to be sure, I just don't want bombs.
When you measure often you can correct it, but for me it isn't worth it.