Hey Shodan.
They are perastaltic pumps, they are brilliant because they are self priming and have a controlled flow rate as well as the added advantage of being pinched or closed when not in use (so acts as a on / off valve so to speak)
The ones i have are just off the shelf items but you could even make one youself with some silicon tube and a servo motor!
I have 4 x SSR's on HABS (Heating Element, Sitrrer Motor and 2 x for Pumps) as well as 2 x DS1820 Temperature Sensors and a Float Switch.
Rob.