Getting good hop/alpha acid efficiency

[netza]

I´ve been having low alpha acid efficiency during my boils so I´ve had to compensate by using way more hops than usual... I always used hop bags which usually float around on top of the wort and never settle down. For my latest brew I used a hop spider, which for those that don´t know is a big net in which you just throw in your hop additions and pull it out once the boil is done. The hops got to settle down and I got lots of IBUs; I used less hops than before but got a lot more bitterness from my hops.
So, basically my question, does the wort absorb less alpha acids if the hops just float on top without settling down?
fyi: I brew all-grain 5 to 10 gallon batches
thanks!

 

[eastoak]

you could just skip the bags and spiders, dump the hops right into the boil.

 

[Mellman]

How are you measuring ibus? talking about the same recipe every time? Fresh hops?

 

[JLem]

I have no empirical evidence for this, but IMHO I think hop bags reduce the amount of contact between the hops and the wort. Also, a hop bag provides a lot of surface area for alpha acids to stick to, so when you pull your hop bag out, you also end up pulling a lot of alpha acids out as well. Alpha acids are notorious for sticking to sides of kettles, fermenters, and even yeast cells. Personally, I don't bother with hop bags for just this reason.

 

[BradleyBrew]

I agree I just chuck the hops in... and majority of the hop / trub end up in the fermenter with 0 ill effects. Not sure why everyone is so obsessed with filtering hops out.

 

[netza]

So just throwing em in means you´ll have to do a whirlpool at the end of the boil right?

 

[netza]

@mellman I started out by measuring them, but seeing how low IBUs I was getting without knowing why, I just started adding hops by experience, after a few batches I sort of knew how much I needed... I know that is way inefficient so that´s why I would rather do things right from now on

 

[JLem]

So just throwing em in means you´ll have to do a whirlpool at the end of the boil right?

Not if you don't want to. I strain my wort through a fine metal colander. Works great. Some folks just dump everything into the fermenter and have had no problems.