The concept of this autofeeder was born from the desire to keep food cold, as it was fed out all day to several exhibits without having to set up a full blown refrigerated feeder like the type pioneered by master aquarist Steve Weast. This automatic feeder system is smaller and cheaper, requires more frequent maintenance, but will achieve the result of keeping food ice cold for 24 hours. The main components of the autofeeder are a thermos, peristaltic dosing pump, and air pump.
For the thermos I selected an Igloo “Legend” 1 gallon beverage cooler. It has a screw top and is all plastic. The pour spout is perfectly sized to fit two pieces of 3/16” rigid airline tubing. I haven’t had to drill or modify it any way.
The peristaltic dosing pump I prefer is a Rola-Chem brand 32gpd chlorine pool pump. Joe Yaiullo suggested these pumps to me a few years ago and I’ve used them ever since without any problems. They have a built-in controller and dose on a repeating 10 minute schedule for a duration that you can easily control, with a minimum dosing time of about 5 seconds or so. The pump draws water from the bottom of the cooler through a rigid airline tubing. I cut the tubing at an angle at the bottom to avoid it sucking on the bottom and creating a vacuum.
Here at the Steinhart Aquarium we use pressurized ‘building air’ to bubble the mixture, but you could use any air pump to do the same. I put a slight bend at the end of the airline tubing so that the feed line doesn’t suck up bubbles. I set the bubbles just high enough to keep the whole thing stirred. Any excess air will just warm up the mixture faster.
Every morning I add two large saltwater ice cubes of about 750mL in volume to the thermos, top it off with system water, and add my food mixture. This varies by the exhibit but generally includes a bit of Cyclopeeze, a lot of newly hatched Artemia nauplii, some Shellfish Diet or PhytoFeast, and other assorted Reef Nutrition products. The big advantage of cooling down Artemia nauplii is that they stay nutritious throughout the day and they are also sluggish and easier for small coral polyps to catch and hang on to.