CONSTRUCTION 



115 



The third type of pool has concrete vertical sides, and may be used 

 either at ground level or above. Diagram is self-explanatory with the 

 exception of one point. Tropical water lilies should have the crown and 



CONCRETE^ 



Fig. 92. Strongly Constructed Concrete Pool 

 Straight sides have some advantages, especially when fishes must be caught in a 

 net. Tender water lilies raise their flowers above the water, which should not be deep. 



soil about 8 to 10 inches below the surface of the water. The tub only 

 needs to be raised on stones as shown if necessary to make this adjust- 

 ment. 



Reinforcement is required if anything more than a light frost is 

 possible. Extra reinforcement at all corners is advisable. While giving 

 advice we could well add the suggestion of having the assistance of an 

 experienced concrete worker, or at least a helper with strong arms and 

 back! 



The base of this pool should be about 6 inches thick and the walls 

 about 5 inches. A slight outward slope to the walls is desirable. 



It is important that concrete work dry slowly. Protect from the 

 sun with litter. Sprinkle if necessary. Forms may be removed in two 

 days. Finishing coat follows immediately. 



All concrete pools should have at least six changes of water over a 

 period of two weeks before introducing fishes or plants. This is 

 important. 



We have seen many amateur-built concrete pools which were off 

 level. This is indeed a sad defect to discover when the first filling with 

 water nears the top. To avoid this embarrassment, attach a good spirit- 

 level to the narrow edge of an ordinary straight board long enough to 

 reach diagonally across corners of pool. Test it between two fixed points 

 that will bring the bubble in the center. Turn board around so that 

 reverse ends will rest on the same points again. If bubble again settles 



