Since then however, I've tried pretty much every combination of water treatment imaginable (mainly using GW's calculator on here, but I've had a go with John Palmer's spreadsheet version too), and I'm still getting the same after-taste. Water treatment does improve the problem slightly, but not enough. So I'm thinking there must be something else going wrong...
I've tried switching HLT, boiler, mash tun, fermenter, and pretty much every other bit of equipment I can think of, so I don't think that's the problem. I clean with oxy and sanitise with StarSan, like many others on here, so I think I'm OK on that score too.
Unless I'm missing something, all that really leaves is sparging or maybe something airborne.
I usually mash in with 2.5L per kg of grain around 66, mash for 60-90 mins, add water to mash out at around 75 (although it usually ends up slightly lower than that, at 72-72ish), drain, and then add the next batch at 75.
I brew in my basement with the back door open. It's far from spotless, but there's nothing obviously any worse than some of the commercial breweries I've visited. A bit damp maybe.
Can anyone offer any suggestions?
Starting to tear my hair out...
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