First time Burtonizer

[ajdelange]

.... I've been wondering just how high you can take sulphate levels without getting a harsh bitterness.

I think that depends on how you personally respond i.e. on what you consider harsh and I think it also depends on the hop cultivar involved. For noble hops to my taste even 30 ppm sulfate is too much. For the English cultivars the tolerable level is appreciably higher.