I recently made a 6% ipa and only used 6g magnum(13%) for 60 mins then added more hops (30g) with 10 mins to go then more in whirlpool under 70 degrees, plus 30g in dry hop for 5 days. The beer has come out exceptionally bitter at first taste but quickly calms down and actually tastes great when the initial bitterness has gone. 6g of magnum shouldn't cause this much bitterness in a 21l batch. When mashing I realised I hadn't sorted my water additions, so in a rush I chucked in some unmeasured gypsum and calcium chloride and I suspect this is what has caused the bitterness. I suspect it's this and not over hopping as it's not a lingering bitter aftertaste (I have made these before!) it's a very astringent almost metallic flavour, that you do get used to, but is ruining an otherwise fine beer. Does anyone know what will have caused this or if it's likely to fade?