Ugh. That doesn't sound like you're having fun.I'm trying to picture what you're talking about with the polycarbonate?
I have tried constant recirc, (a bit of overflow there), tried waiting 10 minutes and then recirculating, etc.
You know, I'm pretty experienced with brewing from stovetop to 3 vessel HERMS to pro breweries, and this Brewzilla is a huge PITA. It's tall, not wide, it requires a hoist, etc- I'm very unhappy with the 'ease' of an all in one like this. It requires another vessel for sparge water (and you can't really sparge in any traditional sense), the pump is anemic, the temperature variation from PID to RAPT (or my trusty thermometer) is huge, the pump clogs if I even consider using hops (bagged or not), the immersion chiller is 1/2 out of the wort in a 5 gallon batch, and more.
I should have bought the 65L even though I only do 20L batches, just for the space. The recirc during the mash wants to overflow each time. I stand there (literally stand not sit!) and babysit it. It's very disappointing, but I'll live with it for sure. The whirlpool arm (extra $) is worthless. The chiller it comes with is worthless. The pump is way undersized and I still can't figure out why it clogged as there was 0 particulate when investigated.
It has a small footprint, that's the only advantage I can think of right now.
Polycarbonate: this photo should help. Remember I have a BZ3, so it is a little different than yours. The tube on the left is clear
I recirc, but not at full throttle. It takes a few minutes to dial in the rate so it does not overflow. Rice hulls help.
I use a spaghetti pot for sparge water, with my sous vide heater set to 170. I agree that traditional sparge is nigh impossible, instead a batch rinse is the best one can do.
The temperatures were waaay off until I calibrated the controller. After that the temperatures, with recirc, stay within 2 degrees. I too would prefer a PID system like an Anvil, but live with the bang bang controller.
I simply do not have space for a 3V system, and cannot accommodate a gas-fired system. I agree this is a very different brew workpath, it takes getting used to.
Definitely get a hoist and attach it to the ceiling. Made all the difference for me, since mine has to sit on a table - the controller is at the bottom.