'J'KOPICAL AQUAKTUM FISHES 



233 



ment, but was abandoned by the writer owing to the trouble of discon- 

 necting everything and washing sand every ten days, which was necessary 

 owing to clogging. In top filter the cotton must be changed every two 

 days, but this can be done in a few seconds. 



This arrangement both filters antl aerates the water. If filtering is 

 not needed, the filter can be removed and aeration will go on. 



B 



Fig. 179. Water Circulatiox by Air Presslrk 



Water can be raised by this method from fifteen to twenty-five inches 

 above level. To secure the greater height, use 34-i"ch inside diameter 

 tube, take plenty of drop and allow eight inches from lowest point to C. 

 By this means and a little ingenuity a return fountain can be made. To 

 secure a uniform flow it would require a small tank to receive the dis- 

 charge from the pipe, and from this an overflow to aquarium in case the 

 water supply comes too rapidly for discharge rate of fountain. 



It is not necessary to carry pipes over edge of aquarium as shown in 

 diagram; they may be carried through the bottom, carrying dirty water 

 directly down. The rise tube should be brought up through inside, over 

 edge of filter. Short pieces of tubing long enough to reach above the 

 sand and to extend an inch below the aquarium base should be used for 

 passing through the slate. A very effective means of securing these in 



