Aquarists use different types of equipment to assist in the running of their aquariums. These can be very important ‘must haves’ such as a protein skimmer and circulation pumps, or labour saving devices such as an automated evaporation top-up device or calcium reactor.
One piece of labour saving equipment is the peristaltic pump. This device originated in the medical profession where medications needed to be applied to patients in precise but low amounts over time. The device has been found to be useful in the marine aquarium hobby and there are models available manufactured for this purpose.
The units vary in size, some perhaps 1″ (circa 25mm) in thickness by perhaps 4″ (circa 1.2mm) square. The ones destined for use with an aquarium are usually constructed of plastic, often with a clear panel on one side. The clear panel enables the owner to see the flexible tube inside.
The unit is powered by a small electric motor which to all intents and purposes is silent. This drives a shaft which revolves very slowly. As it revolves it usually drives three arms and on the end of each arm is a roller. A flexible tube about ¼” (circa 7mm) in diameter enters at one side of the unit and exits from the same side but the other corner. The flexible tube goes in a circle within the unit. When running, the rollers which are moving slowly in a circle compress the flexible tube and force any liquid present forwards in the same direction.
The pumps can be obtained in various outputs and with either static or variable speed. The static speed ones are of course less expensive. They run very cheaply on mains electricity and can be used with electric timers. Fitting them is simplicity itself, most being fitted upright in a convenient location out of sight but accessible and away from the danger of getting wet from seawater. The intake end of the tube should be fitted with a filter which is easily constructed – a small piece of fine filtration sponge with a narrow hole is the often used method. The outlet end of the tube could need holding down with a sucker or small weight as it might tend to float to a horizontal position.
The aquarist can make use of the pumps in several ways. Sometimes it is difficult to adjust the flow rate of an anti-nitrate filter (a de-nitrator) and a pump could be selected to move seawater through the filter, thus solving the problem. Or, provided the aquarist knows the demand of the aquarium, supplements could be applied for the appropriate period per day to meet the need. A watch would need to be kept that mixtures remained viable, that is did not de-mix over time, and also that clogging did not occur.
One area that the pump cannot be used for is timed feeding. This is a great shame as it is ideally suited and could successfully dose an aquarium accurately according to the demand of the livestock. So why can’t it be used? It is simply because the food goes off. The pump needs a small reservoir so that timed feeding can occur. During this time the liquefied food morsels could fall to the bottom of the reservoir, though the problem could be avoided by a simple stirring system. As said though, when waiting to be used the food deteriorates. Experiments have been made with refrigeration devices, all by aquarists but as far as I know a successful solution has not been found. If feeding could be done with the aid of the pump then more natural feeding over the daylight hours could be accomplished, rather than the one or two heavier meals a day that usually occurs.
There is very little to go wrong with a peristaltic pump. The item to watch is the flexible tube inside the pump in the region where it is compressed. Over time it starts to fail and needs replacement. The tube is not expensive and so a length can be kept as spare. Some manufacturers supply this spare tubing with a new pump.
So if the aquarist is having difficulty in supplying a correct flow rate or wants to apply precise amounts of liquid to the aquarium a peristaltic pump could be considered.