ready to boil wort but how much columbus hops to add ?

[varadamo]

evening all - doing a biab this evening using a peco boiler - 75 mins just up and about to take out the grain - have plenty of time during the boil to get an answer for this  - recipe says add 25.5 ibu hops of your choice - ive only columbus - how much do i add ?
thanks

[pob]

What year are they? How have they been stored?

What's the Alpha Acids AA% on the pack?

What volume are you brewing?

I can then BeerSmith it for you (& work out hop storage loss)

[varadamo]

great thanks pob - nearly boiling !     they are 2013 and vacuum packed  - aa is 17.5  volume 23 litres wort  - cheers

[pob]

Rough guide

Your hops are nearly a year old at this stage, so using:

http://brewerslog.appspot.com/HopAlphaCalc

It suggests an AA% of 11.9, based on 300 days, vacuum sealed, stored at 5°C (fridge).

Into BeerSmith, you would need approx 19g with 5kg grain or 20g with 6kg grain at 60mins to give you 25 IBUs (don't know your grain bill or beer style).

Next step, kick yourself in the arse (in fact do it twice) for not doing your homework beforehand, it take less than 10 mins to work out with BeerSmith. (Ask here if you need help in the future, and at least before you start).

[varadamo]

ya feckin star ya - i know i know i know - second time using biab - had help with me first time - note to self - should sign up to beersmith / thank pob / get back to the boiler !