Here's my version of an airtight, continuous feed calcium hydroxide mixing chamber. Mine is square and made of acrylic scrap. Total cost of acrylic was about a dollar per side, or about $6 to $8. Dimensions are 5 1/4' x 5 1/4' x 24' tall. I put the pump on the inside. The pump slides onto a cleat on the inside of the chamber. The cord runs out through a bulkhead. The top of the reactor is removable for servicing the pump and is sealed with a homemade square rubber gasket. Kalk is added through a pop-top soda bottle cap. I cut the top off a soda bottle and epoxy'ed it into a hole in the

top. I use anelevated purified water reservoir to provide the head pressure and the drip is regulated with a plastic air valve. I put some triangles in the bottom of the chamber to create a roundish bottom. The pump is on a timer and runs for a few minutes four times per day. I used a 'tap' to cut pipe threads into the sides of the chamber and screwed in the nipples for the purified water in and kalkwasser out. No leaks!