CONSTRUCTION 113 



a few handfuls of earth stirred in the water and allowed to stand several 

 hours or days will make the job tight. Occasional stirring of the dirty 

 water helps. Before filling with water the white lead should be allowed 

 two days to harden. 



If in a place where freezing will not occur, wooden tanks should be 

 filled all winter. Bad open seams in dry old tanks usually close by wet- 

 ting for a week. 



Weight of Water. With large tanks the weight of the water is some- 

 times a serious matter to reckon with. A gallon weighs 8 1/3 pounds. 

 As before stated, the gallon capacity is calculated by multiplying the 

 inch height, breadth and length together and dividing the result by 231. 

 For instance, a tank 20 inches deep, two feet wide and six feet long would 

 be computed in this way: 20 X 24 = 480 X 72 = 34,560, divided by 231 

 = about 150 gallons, which, multiplied by 8 1/3 = 1250 pounds. 



CONSTRUCTION OF TANKS AND POOLS 



Three types of pools will be considered, each suited to different 

 conditions and requirements. The first is the simplest, which is merely 

 a hole dug in the ground. It is the kind used by a number of com- 

 mercial goldfish farms. It is inexpensive and makes possible the rapid 

 expansion of pond capacity as requirements demand. Furthermore gold- 

 fishes do extremely well in a soil bottom— probably better than in cement. 



If the soil is porous, it will be necessary to have an available supply 

 of water, or else the surfaces must be puddled with clay. The depth 

 should be about three feet, the water being filled to not over two feet to 

 avoid overflow during heavy rainfall. If water rises, it should be drawn 

 off to standard level. Make one corner of the pond lower than the 

 others. Fishes are caught in nets after water has been drawn off so 

 that it is standing only in the low corner. Large establishments use 

 pumps for reducing water level. For winter storage of hardy goldfishes, 

 have the pond water two feet deeper than the prevailing frost line for 

 your part of the country. Soil bottom ponds can, of course, be made 

 any size, but fish farms usually have them about 30x40 feet and arranged 

 in rows. A large farm will have perhaps a hundred or more such ponds. 



Of course water in a goldfish pond with a mud bottom is cloudy, 

 the fish are hard to see and it is a messy job cleaning it out. Where 

 ponds are smaller and economy of construction not so important, one 

 might well adopt the second type shown in figure 91. This is a sloping- 

 side, fairly deep (2 or 3 ieeb) concrete pool with walls about five inches 

 thick. Reinforcing is not always necessary, but nevertheless a layer of 

 heavy chicken or fencing wire within the concrete gives a margin of 



