My first two attempts (berliner-weisse and lime gose) weren't sour enough (ph 4) after up to two days, after which I got nervous and added some acid. I'm using goodbelly mango plantarum. I think I figured out what the problem was--heat variation in the kettle causing hot spots and overshooting. I came up with a simple solution--plug the pump in series with the mash heater. That way whenever the heater goes on the pump goes on. Need to carefully wrap cling wrap so that the pump entry doesn't create oxygen ingress.
All you need is a two + tap power strip, and an IEC AC power cable (many common electronics devices use these). Plug the power strip into the mash heater output of the controller, plug the IEC cable and heater into the power strip, and plug the pump into the AC receptacle of the IEC cable. Make sure the controller is on mash and there you go. Seems to work well to completely avoid hot spots. This probably won't work with the second gen proportional controller.