Let see, I can run the vacuum cleaner or contemplate a question. I choose the latter.
Smokers work because they balance fuel-heat-air, aka, the fire triangle. Higher temps require more air and will burn available fuel faster. Lower temps the opposite.
The water pan filled with water is a heat sink to help keep temperatures stabilized lower due to the heat absorption properties of water and the "state" change that occurs at 212F. Water expands about 1600 times in volume as it changes from a liquid to a gaseous state at 212F, aka turning to steam. Ever wonder why the
WSM instructions say to leave the top vent fully open? It is due to the steam. The last thing you want when wet smoking is a slight overpressure in a steam filled smoke chamber if the steam does not have an easy escape point at the highest point in the chamber. When you remove the lid instant expansion occurs and you can get scalded.
Low temperatures for the water filled
WSM are 200-250F. You can get higher temps with a wet smoke but are burning more fuel than you would with a dry water pan and can potentially hurt yourself if you are not careful.
So lets talk dry water pans or pans filled with a clay saucer or sand.
Dry smoking (no water) still allows temps to be set from 200-350 or more, you just have to be more aware of how you control temps with the vents. I dry smoke exclusively and most of my stable, targeted smoke temps are between 250F and 350F, but I have smoked at 225-235 too. I haven't used a clay saucer or sand yet, just going with a dry water pan to act as a minor heat sink and a major heat deflector.
I control my temps with all four vents, generally setting them ALL the same depending on what temp I want. Less open for lower temps, more open for higher temps. When I want at target temp of 275-280F my vents are about 1/3 open bottom and top on my rather leaky relatively new
WSM (horrible door fit). Each
WSM will be a little different. At 225-235F my bottom vents were only about 1/8th open with the top vent just a little more. The top vent pulls or restricts air flow through the bottom vents because heat rises. Opening it pulls more air, burning more fuel, making it hotter; closing restricts air flow, slows the fuel burn, and cools temps. Top vent movements are minor though. Once I get your my temps stabilized I generally just adjust the top vent 1/16" to 1/8" at a time to catch any movements I see on my Maverick, but it will stay stabilized for hours.
Clay or sand in the dry water pan helps "delay" temp swings because the clay or sand heats up and reaches thermal equilibrium with the heat in the chamber, no different than your dry water pan does. Basically you are adding more mass to heat up or cool down. With or without clay or sand you can run the WSM as hot or as cool as you want controlling the temp with the vents. I also burn less fuel on a dry smoke than I would wet compared to what the WSM instructions say.
Okay, that's it. Time to go run the vacuum. Have fun smoking, wet or dry, clay, sand, or just empty water pan!