Is my low brew house efficiency due to the Bazooka screen ?
Is a false bottom better for this purpose ?
Possibly. You can’t know without a full set of measurements. Grist weight, strike volume, sparge volume, first and last runnings gravities, etc.
Only if you’re fly sparging.
yes I am fly sparging
There is no mention of how large the mashing vessel is and the length of the screen. If the vessel is much longer than the screen, then might have some effect. But, I find that the most influential variable for efficiency is the length of time used for the runoff and sparging. The longer the time, the higher the efficiency. Go slow.
You haven’t described the geometry of your mash tun or your bazooka screen. See John Palmer re proper manifold design for fly sparging http://www.howtobrew.com/appendices/appendixD-1.html
For troubleshooting brewhouse efficiency generally go to http://braukaiser.com/wiki/index.php?title=Troubleshooting_Brewhouse_Efficiency
I use a double bazooka screen (the T kind which is about 12 inches long) in a converted 15.5 gallon sanke keg and I consistently get 85% efficiency out of it. I fly sparge and usually take about 45 minutes to get 13 gallons in the kettle.
I use a braided hose probably 20 or so inches in circumference and get 83% fly sparing and 68% batch sparging. What efficiency are you getting? System?
Wow, that’s a huge difference. I got 86% on a batch sparge yesterday. Wonder why you get such a difference.
What color is your mash tun?
I don’t know either. I actually got 71% on Monday but I did some pre-boil calculations and decided to boil for 90 minutes to get it there. My out tube is pretty small 3/8"? I think. Could a slower b/c of constricted tube cause lower efficiency. Like I said, same system gets me 83% when I fly sparge for an hour.
What’s your conversion efficiency? It sounds like you aren’t finished at the end of the mash rest, and the long sparge is giving you extra time to get full conversion.
I use a keggle with a 12’’ bazooka screen. There is no dead space.
Agree, that’s a huge difference and doesn’t jive with my experience at all. I get around 80% batch sparging using a braid in a stainless “keggle”.
That’s a good thought, Sean. I guess the hat didn’t kill your brain after all! 
If I’m not mistaken, I was sitting just to the right of Sean in that picture. He was doing a fair job of killing brain cells at the time.
Not sure what conversion efficiency is but I mash for 60-90minutes, depending on the beer and always raise my mash to 168 by adding boiling water to stop conversion/allow for better sugar extraction. For batch sparging I drain and then add my sparge water and drain again. I do this as fast as possible but like I said my outlet tube is small. Maybe it’s not draining fast enough. I don’t mind. I just set my efficiency on Hopville to 70% when I know I’m going to batch sparge and I get good results.
I think that one is from Club Night, but from a brain-cell-killing standpoint, the entire weekend was pretty ambitious. I was a little worried, but I look at Denny and… Wait, what was I talking about?
In batch sparging, the speed of runoff makes no difference to your efficiency. Do you stir in the sparge water really well?