I had purchased a used 110 gal Baine Marie that the previous owner had burnt the oil in. Due to this thick sludge build up caked on the inner jacket it had terrible heat transfer. I brought it back and power flushed it for a week alternating with Dawn dish soap, PBW and citric acid. After about 1 week it looked brand new on the inside. I then converted it from a oil Baine Marie to a stand alone steam boiler. The steam is much more responsive, cleaner and cheaper.
I modified the sight glass so I could read all the way to the bottom of the jacket. I fill my water to just 1 inch above the 4- 6000 watt elements. I have also added a auto-vent, low water cutoff, auto-feed, low pressure relief valves, vacuum relief valves and a high pressure cut-off switch. Been running it for a couple of years and it runs like a champ