MINIATURE CIRCULATING SYSTEMS 

 FOR SMALL LABORATORY AQUARIUMS 



By C. M. Bredcr, Jr. 



The American Museum of Natural History, New York, N.Y. 



Abstract. — Methods are given for constructing both an open system, wherein the sea 

 water runs to waste, and a closed system, wherein the water is recirculated. Easily 

 available materials are used, and all devices, such as a constant-level siphon and an 

 automatic shutoff, are simple to assemble. Each of the systems is designed so as to 

 require a minimum of maintenance. Equipment necessary for the control of sea water 

 is discussed. 



Because of the requirements of certain 

 experiments it became necessary to estab- 

 lish various small, but fully controllable 

 circulating systems in small aquariums. 

 These have included both open and closed 

 fresh-water systems and closed salt-water 

 systems. As the designs eventually 

 worked out have proved to be entirely sat- 

 isfactory, and as many colleagues have in- 

 quired about these systems, with a view to 

 building similar ones for their own pur- 

 poses, the details of construction and op- 

 eration are explained here. 



Primarily these systems are the out- 

 growth of work of earlier years at the old 

 New York Aquarium, where much larger, 

 but similar, equipment formed the basis 

 of operations. This equipment itself had 

 been developed from schemes used by 

 older institutions of similar kind. Nat- 

 urally, many persons had a hand in devel- 

 oping the arrangements and devices em- 

 ployed at the New^ York Aquarium. For 

 these reasons the origins of the devices 

 were not always clear, but those chiefly 



This article is a revision of an article that 

 appeared in Zoologica, Scientific Contributions 

 of the New York Zoological Society, vol. 42, 

 part 1. May 20, 1957, with an addendum by the 

 author. 



interested and responsible for them at the 

 Aquarium were C. W. Coates and the late 

 C. H. Townsend, and H. Knowles. Town- 

 send (1928) and Breder and Howley 

 (1931) reported on some of these features. 

 It has been found that by suitable modifi- 

 cation of the principles of the larger de- 

 vices it is possible to develop very useful 

 miniature equipment. Such need, of 

 course, applies only to laboratories which 

 are not connected with large public 

 aquariums and which consequently lack 

 the utilities usually to be found only ii^ 

 such places. These devices have been 

 worked out in connection with experi- 

 mental work carried on in the laboratories 

 of the Department of Fishes and Aquatic 

 Biology of the American Musemn of Nat- 

 ural History, which has been supported 

 in part by the National Science Founda- 

 tion. 



OPEN SYSTEMS 



An "open system," as the term is used 

 here, is one in which the water is used 

 once and is not recirculated ; there is only 

 a supply line and a drain line. This calls 

 for little comment in present connections 

 except where a very small, well-regulated 

 flow is required. Such apparatus may be 



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