I had my doubts as to whether the PG500 could actually cold smoke but I am now a believer.
I have been cold smoking salmon to make lox for 30+ years, using various configurations of cold smokers. Most recently, I ran a 25' dryer vent tubing from the smoke stack of my GMG DB into the bottom vent of my big green egg where I placed the salmon and an ice pan.
If truth be told, I did configure my tubing to attach on to the proprietary smoke stack of the PG500 just in case but it will not be necessary to go back to this method.
Following my usual procedure of salting (Kosher non iodized salt) the side of salmon for 6 hours, rinsing and drying with a towel, and then air drying for 2 hours with two table fans (on opposite sides of the salmon) until a scab (the pellicle) forms. The firmer the scab, the better the smoke adherence.
Then into the smoker, set to 170°, 10,10 for 6 hours. The salmon was placed on a wire rack (12x18) that fit perfectly in the cold smoke drawer.
The air temperature was 71° when I started at 3 pm, the grill was in the shade, and now, 5 hours into the cook at 8 pm, it is air temperature 62°, cold smoke drawer temperature of 55° and controller reading 142°.
I used a 9x13 pan with water frozen about 2/3 full (it takes at least 2 days for the water to freeze solid) placed on the railings just above the cold smoke drawer. I could have placed my second pan of ice side by side with the first but that would have closed any opening to allow smoke through. So I opted for another place, on the grate of Zone 4, for it.
I used the convenient thermometer opening to place the pit probe of my Maverick 732 just above the salmon.
The cook: it took an hour for the grill to reach 170°, overshot by 5°, and then quickly came down. Most of the time the controller read in the 150°'s range with an occasional leap into the 160°'s.
The temperature in the cold smoke drawer peaked once at 61° but mostly held 59° during the day (I started the smoke at 3 pm) and then settled in at 55°-57° for the last three hours. Fantastic temperature for cold smoking. I felt the salmon and it is still very cold.
The ice pan on the Zone 4 rack was completely melted after 4 hours but still cold. I still have an hour to go so do not know what the ice has done below the drip pan but the temperature down there remains 57° so all is well.
There has been an abundance of smoke, more than I am used to. The flame went out a couple of times each hour but rekindled itself from 135°-145°, well before the igniter went back on. So there were times when pellets dropped into the pot without flame, must have accumulated and then the temperature rose several degrees quickly when the pellets ignited again.
My concern was that the salmon would be too smokey, given how much smoke continually poured from the smoke stack doors et al. I was tempted to pull it after 4 hours but decided to wait out the 6 hours so I have an apples to apples comparison with my usual method.
At 10, 10 pellets did not always drop when the auger turned for such a brief moment. But enough tinkled into the fire pot to maintain the average 150° temps, well below the controller set 170°.
I removed the salmon at 5 1/2 hours and shut down the grill. There was still about 1/4 of the ice remaining in the pan below the drip tray. The water in the upper tray was now lukewarm. Amazing that the cold smoke drawer was so isolated from the heat of the grill. The salmon was still very cold to the touch. It smelled like sweet smoke and I could hardly wait until morning to sample some.
It was absolutely delicious although my wife did believe it was too smokey. I'll probably cut the smoke time to 4 hours next time.
Here's some photos showing an initial placement of both ice pans atop each other but I was concerned of the top one losing its shape and spilling water on the salmon (cheap disposable aluminum) but it shows the positioning of the first ice pan.
For breakfast, I had the lox (slice as paper thin as possible) on Kavli cracker (one of the few carbs I eat) and had the smoked salmon salad (sliced thin enough to see some lettuce behind it) for lunch.
I replaced the drip pan and grate for the second ice pan.
Smoked Salmon with Salad Vinaigrette for lunch.