Heat rises, use your top tub for thermostat and thermometer probes.
I disagree. You should monitor all your tubs with everything up and running for a little while and figure out which is warmest in your particular rack. I cannot explain why but the top tub in one of my racks is cooler than every other tub except the bottom one. I use the warmest tub (second from top) on that rack for my thermometer and probes.
You disagree that heat rises?![]()
So do you run your flexwatt under the tubsor behind them???