Grainfather hop filter

[gr_baker]

I've finally had time to sit down and work out the change in hop weights due to reduced utilisation caused by a hop spider. Following this article https://www.grainfather.com/blog/week-5 ... hop-spider there's some formula to work out the weight of hops required to hit a certain IBU. I worked through the numbers in the example they gave and reduced the utilisation by 8%. The hops weight required went up by around 8% too. So I think that from the bittering point of view it's safe to just multiply the weight by around 8%.

However, most of our recipes have late hops for aroma and flavour. It's probably safe to assume that the hop spider will reduce the flavour/aroma by the same amount and multiply these by 8% too to hit the target IBU.

The Brulosophy article is here http://brulosophy.com/2016/03/21/kettle ... t-results/ They used a nylon bag rather than a spider but I expect that the effect will be similar. The biggest puzzle though was why the tested IBU is so much lower than Beersmith indicates even for the loose hops. There's a big discussion and a link to another discussion with a lot of input from Graham Wheeler on the ineffectiveness of Tinseth in calculating IBU. It's a different discussion but the effect of the hop spider may be small compared to the inaccuracy of the IBU calculation in the first place.

[Fil]

Perhaps you can minimise any loss in hop utilisation by using the pump to recirculate the boil through the hop spider, if using a double walled tight nylon mesh grain bag keep an eye on the level in the bag and throttle back the flow as necessary, Ive not done this with the g/f yet but the larger brewkits lil brown solar pump does the job ok.

[Fil]

Perhaps you can minimise any loss in hop utilisation by using the pump to recirculate the boil through the hop spider, if using a double walled tight nylon mesh grain bag keep an eye on the level in the bag and throttle back the flow as necessary, Ive not done this with the g/f yet but the larger brewkits lil brown solar pump does the job ok.

[sbond10]

If hop spiders are bad why do we bag um up surly that does the same ?