Hopback Question

[RedHornBrew]

My brewery came with a hopback that I've been using as a CIP vessel, but have decided to start playing around with it.
I have never used a hopback before, and am looking for guidance.
The vessel is 30 gallons, closed top Stout hopback. I will be using it with a few IPA's to start, and would like to know what to expect before I jump in.
My knock out is usually at about 200 degrees, I am expecting some isomerization, but how much bitterness is actually extracted through this process?
My other question is how to determine the proper amount of hops to put in the vessel. I'll be using whole leaf hops, but am not sure if I should fill up this huge vessel half full, quarter full, three quarters full?

Any words of guidance are appreciated!

[schmogger]

You will mainly get aroma and favor form the hop back so I would not worry about the bittering aspect. What size batches are you doing? You can start with doing 1/2 lb per barrel and see how it goes and either work your way up to more # or less depending on what the results are from the first batch.

[RedHornBrew]

You will mainly get aroma and favor form the hop back so I would not worry about the bittering aspect. What size batches are you doing? You can start with doing 1/2 lb per barrel and see how it goes and either work your way up to more # or less depending on what the results are from the first batch.

My Stout system is oversized, so it is listed as a 7bbl, but I can usually pull 8bbl batches out of it.

[drewseslu]

I calculate my hopback additions at 5% utilization, and rates range from about .5-1.5lbs/bbl.

[NHBrewer23]

I run a 20 bbl brewhouse and have used 20lbs. of whole leaf without issue. Our hopback has a 2bbl capacity. For utilization, I claim 0% as the wort is being passed through and immediately sent into the heat exchanger. On a side note, I do use a 5% utilization rate during whirlpool and rest additions.