A gravity mismatch is really common, and it almost always comes down to one thing: your actual brewhouse efficiency is different from what the recipe assumed.
We typically see efficiencies between 70–85% on Grainfather systems. Where you land depends on a few things - your mash pH, how fine your grain's crushed, how much speciality grain is in the mix, and how well your sparge pulls the sugars out.
A few things that'll help going forward:
- Take gravity readings through the brew day, not just at the end - that way you can see exactly where things shift.
- Work out your actual brewhouse efficiency from your last brew. You'll need your grain bill's potential gravity, your OG before pitching yeast, and your volume into the fermenter — that's enough to calculate it and use going forward.
- Or keep it simple - nudge the efficiency setting in the app up or down each brew until your predicted and actual numbers line up.
Once your efficiency's dialled in, the app gets noticeably more accurate for your setup. Every system runs a little differently, so it's less about getting it "right" and more about getting it right for your brewery.
Still not lining up after a few brews? Get in touch with our team, and we'll help you work through the numbers.