AQUARIUM CONSTRUCTION 217 



Stopping Leaks. Large aquaria nearly always leak a little at first, 

 or after moving them, or even after emptying without moving. This 

 usually corrects itself within a few days, but, as elsewhere directed, it 

 can nearly always be stopped by making the water very muddy. The 

 particles of dirt get into the leak and choke it up. This may require 

 several days. The water should be stirred occasionally. 



Aquarium Cements. The prime requisites of an aquarium cement 

 are resistence to water, adhesiveness, moderately quick setting with- 

 out ever becoming stone-hard, and being non-poisonous. A cement 

 combining these qualities is composed of one quart polishing or other 

 fine sand, one quart Plaster of Paris, one pound litharge, two ounces 

 powdered resin ; mixed with boiled linseed oil to a consistency of putty 

 suitable for glazing. This cement has been found to be good for 

 both fresh and marine water aquaria. A durable cement for those 

 who cannot obtain fine sand is made of equal parts by weight of zinc 

 white, whiting and litharge, mixed with boiled linseed oil to a firm 

 but tacky consistency. 



CONCRETE AQUARIA 



The making of concrete aquaria opens a new and an unlimited 

 field. Those who have felt that the metal-frame aquarium is hope- 

 lessly restricted and commonplace can here find more room for indi- 

 vidual expression, design and achievement. The illustration facing 

 page seven gives an idea of possibilities along this line. 



As individual ideas will vary so widely in the design of concrete 

 aquaria, only a few (yet important) directions can be given. Cement 

 should be of the highest grade, fresh and free from lumps. A mix- 

 ture of one part cement to two of clean, sharp sand is about right. 

 Wooden forms ought to be soaked with water just before using, or 

 else thoroughly paraffined. Cement mixture should be wet enough 

 to just pour, and needs to be well tamped to avoid bubbles. Rein- 

 forcement rods (54-inch diameter) are essential, especially around the 

 top edge, where a continuous band should be formed. Through the 

 bottom the bars should be wired together, forming 4-inch squares. 

 Do not be in a hurry to get the forms off. The whole job should be 

 moistened for a day and allowed to stand for two more days if their 

 removal is going to cause any strain. Glass must not be embedded 

 directly in the concrete, but provision made for later setting it in with 

 ordinary aquarium cement. If sides do not support the glass evenly 

 they should be cut away or built up until they do. Otherwise glass 

 is sure to crack when the soft aquarium cement yields to the water 



