I added a small cheap pump to automate whirl-pooling while I run my immersion chiller. I start to run it during the last 10 minutes of the boil to sterilize the pump/tubing/etc. It seems to get the wort down to mid 20’s C in around 15 minutes.
In future I’m looking at automating sparging with it as well. I plan to add a high/low level sensor around 1″ apart. When the level hits the low sensor it would pump till its back to high. This seemed simpler than trying to match flow rates exactly on input/output.
DC 12V Electric Centrifugal Water Pump 109 GPH (P-38E) $22 USD shipped
AC to DC 12V 1A Power Supply $2.49 USD shipped