When changing up your process by suddenly deciding to underlet the mash in your BIAB kettle, DON'T forget that your HLT has been sitting idle for a few months. Sticky mess on the bottom not discovered until lid was off and water was running in. No biggie, stop the pump and scrub it out. Start water again, then try to figure out what the heck is coming out of the valve. Large green mold blob, that's what. After frantic search to find the brush that fits in the valve, scrubbing it out with hot hot hot water and rinsing several times, finally good to go. Added 30 minutes to what should have been a quick brewday. Yah, don't do that.